#C 168 ,145,144,141 bytes

EDIT: Tried init 'i' to 1 like so

a,b;main(i)

To get rid of leading whitespace,
but it breaks on input starting with three, seven or eight

141

#define s|a%1000== a,i;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b%32<<5*i++)if(i>4|a%100==83 s 138 s 116 s 814 s 662 s 478)a=i=0;} 

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144

a,i;main(b){for(;~(b=getchar());printf(" %c"+!!i,b),a=a*21+b-100,++i)if(i>4|a==204488|a==5062|a==7466|a==23744|a==21106|a==6740|a==95026)a=i=0;} 

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168

i,a;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4|a==1869768058|a==6647407|a==7305076|a==1920298854|a==1702259046|a==7891315|a==1701734766)a=i=0;} 

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Ungolfed

i,a;main(b){ for(;~scanf("%c",&b); // for every char of input printf(" %c"+!!i,b), // print whitespace if i==0 , + char a|=b<<8*i++ // add char to a for test ) if( i>4| // three seven eight a==1869768058| // zero a==6647407| // one a==7305076| // two a==1920298854| //four a==1702259046| //five a==7891315| //six a==1701734766 //nine ) a=i=0; //reset i and a } 

int constants gets unnecessary large by shifting a<<8
but in case you can compare to strings somehow it should be the most natural

146 Using string comparison

#define s|a==*(int*) a,b;main(i){for(;~(b=getchar());printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4 s"zero"s"one"s"two"s"four"s"five"s"six"s"nine")a=i=0;} 

Using String comparison

Obfuscated

#define F(x)if(scanf(#x+B,&A)>0){printf(#x,&A);continue;} B;A;main(i){for(;i;){B=1;F(\40e%4s)F(\40th%3s)F(\40se%3s)F(\40o%2s)B=2;F(\40tw%1s)F(\40si%1s)B=1;F(\40%4s)i=0;}} 

C 168 ,145,144,141 bytes

EDIT: Tried init 'i' to 1 like so

a,b;main(i)

To get rid of leading whitespace,
but it breaks on input starting with three, seven or eight

141

#define s|a%1000== a,i;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b%32<<5*i++)if(i>4|a%100==83 s 138 s 116 s 814 s 662 s 478)a=i=0;} 

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144

a,i;main(b){for(;~(b=getchar());printf(" %c"+!!i,b),a=a*21+b-100,++i)if(i>4|a==204488|a==5062|a==7466|a==23744|a==21106|a==6740|a==95026)a=i=0;} 

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168

i,a;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4|a==1869768058|a==6647407|a==7305076|a==1920298854|a==1702259046|a==7891315|a==1701734766)a=i=0;} 

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Ungolfed

i,a;main(b){ for(;~scanf("%c",&b); // for every char of input printf(" %c"+!!i,b), // print whitespace if i==0 , + char a|=b<<8*i++ // add char to a for test ) if( i>4| // three seven eight a==1869768058| // zero a==6647407| // one a==7305076| // two a==1920298854| //four a==1702259046| //five a==7891315| //six a==1701734766 //nine ) a=i=0; //reset i and a } 

int constants gets unnecessary large by shifting a<<8
but in case you can compare to strings somehow it should be the most natural

146 Using string comparison

#define s|a==*(int*) a,b;main(i){for(;~(b=getchar());printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4 s"zero"s"one"s"two"s"four"s"five"s"six"s"nine")a=i=0;} 

Using String comparison

Obfuscated

#define F(x)if(scanf(#x+B,&A)>0){printf(#x,&A);continue;} B;A;main(i){for(;i;){B=1;F(\40e%4s)F(\40th%3s)F(\40se%3s)F(\40o%2s)B=2;F(\40tw%1s)F(\40si%1s)B=1;F(\40%4s)i=0;}} 

#C 168 ,145,144,141 bytes

EDIT: Tried init 'i' to 1 like so

a,b;main(i)

To get rid of leading whitespace,
but it breaks on input starting with three, seven or eight

141

#define s|a%1000== a,i;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b%32<<5*i++)if(i>4|a%100==83 s 138 s 116 s 814 s 662 s 478)a=i=0;} 

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144

a,i;main(b){for(;~(b=getchar());printf(" %c"+!!i,b),a=a*21+b-100,++i)if(i>4|a==204488|a==5062|a==7466|a==23744|a==21106|a==6740|a==95026)a=i=0;} 

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168

i,a;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4|a==1869768058|a==6647407|a==7305076|a==1920298854|a==1702259046|a==7891315|a==1701734766)a=i=0;} 

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Ungolfed

i,a;main(b){ for(;~scanf("%c",&b); // for every char of input printf(" %c"+!!i,b), // print whitespace if i==0 , + char a|=b<<8*i++ // add char to a for test ) if( i>4| // three seven eight a==1869768058| // zero a==6647407| // one a==7305076| // two a==1920298854| //four a==1702259046| //five a==7891315| //six a==1701734766 //nine ) a=i=0; //reset i and a } 

int constants gets unnecessary large by shifting a<<8
but in case you can compare to strings somehow it should be the most natural

146 Using string comparison

#define s|a==*(int*) a,b;main(i){for(;~(b=getchar());printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4 s"zero"s"one"s"two"s"four"s"five"s"six"s"nine")a=i=0;} 

Using String comparison

#C 168 ,145,144,141 bytes

EDIT: Tried init 'i' to 1 like so

a,b;main(i)

To get rid of leading whitespace,
but it breaks on input starting with three, seven or eight

141

#define s|a%1000== a,i;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b%32<<5*i++)if(i>4|a%100==83 s 138 s 116 s 814 s 662 s 478)a=i=0;} 

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144

a,i;main(b){for(;~(b=getchar());printf(" %c"+!!i,b),a=a*21+b-100,++i)if(i>4|a==204488|a==5062|a==7466|a==23744|a==21106|a==6740|a==95026)a=i=0;} 

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168

i,a;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4|a==1869768058|a==6647407|a==7305076|a==1920298854|a==1702259046|a==7891315|a==1701734766)a=i=0;} 

Try it online!

Ungolfed

i,a;main(b){ for(;~scanf("%c",&b); // for every char of input printf(" %c"+!!i,b), // print whitespace if i==0 , + char a|=b<<8*i++ // add char to a for test ) if( i>4| // three seven eight a==1869768058| // zero a==6647407| // one a==7305076| // two a==1920298854| //four a==1702259046| //five a==7891315| //six a==1701734766 //nine ) a=i=0; //reset i and a } 

int constants gets unnecessary large by shifting a<<8
but in case you can compare to strings somehow it should be the most natural

146 Using string comparison

#define s|a==*(int*) a,b;main(i){for(;~(b=getchar());printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4 s"zero"s"one"s"two"s"four"s"five"s"six"s"nine")a=i=0;} 

Using String comparison

Obfuscated

#define F(x)if(scanf(#x+B,&A)>0){printf(#x,&A);continue;} B;A;main(i){for(;i;){B=1;F(\40e%4s)F(\40th%3s)F(\40se%3s)F(\40o%2s)B=2;F(\40tw%1s)F(\40si%1s)B=1;F(\40%4s)i=0;}} 

#C 168 ,145,144 bytes

144

b,a;main(i){for(;~(b=getchar());printf(" %c"+!!i,b),a=a*21+b-100,++i)if(i>4|a==204488|a==5062|a==7466|a==23744|a==21106|a==6740|a==95026)a=i=0;} 

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168

i,a;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4|a==1869768058|a==6647407|a==7305076|a==1920298854|a==1702259046|a==7891315|a==1701734766)a=i=0;} 

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Ungolfed

i,a;main(b){ for(;~scanf("%c",&b); // for every char of input printf(" %c"+!!i,b), // print whitespace if i==0 , + char a|=b<<8*i++ // add char to a for test ) if( i>4| // three seven eight a==1869768058| // zero a==6647407| // one a==7305076| // two a==1920298854| //four a==1702259046| //five a==7891315| //six a==1701734766 //nine ) a=i=0; //reset i and a } 

int constants gets unnecessary large by shifting a<<8
but in case you can compare to strings somehow it should be the most natural

146 Using string comparison

#define s|a==*(int*) a,b;main(i){for(;~(b=getchar());printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4 s"zero"s"one"s"two"s"four"s"five"s"six"s"nine")a=i=0;} 

Using String comparison

#C 168 ,145,144,141 bytes

EDIT: Tried init 'i' to 1 like so

a,b;main(i)

To get rid of leading whitespace,
but it breaks on input starting with three, seven or eight

141

#define s|a%1000== a,i;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b%32<<5*i++)if(i>4|a%100==83 s 138 s 116 s 814 s 662 s 478)a=i=0;} 

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144

a,i;main(b){for(;~(b=getchar());printf(" %c"+!!i,b),a=a*21+b-100,++i)if(i>4|a==204488|a==5062|a==7466|a==23744|a==21106|a==6740|a==95026)a=i=0;} 

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168

i,a;main(b){for(;~scanf("%c",&b);printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4|a==1869768058|a==6647407|a==7305076|a==1920298854|a==1702259046|a==7891315|a==1701734766)a=i=0;} 

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Ungolfed

i,a;main(b){ for(;~scanf("%c",&b); // for every char of input printf(" %c"+!!i,b), // print whitespace if i==0 , + char a|=b<<8*i++ // add char to a for test ) if( i>4| // three seven eight a==1869768058| // zero a==6647407| // one a==7305076| // two a==1920298854| //four a==1702259046| //five a==7891315| //six a==1701734766 //nine ) a=i=0; //reset i and a } 

int constants gets unnecessary large by shifting a<<8
but in case you can compare to strings somehow it should be the most natural

146 Using string comparison

#define s|a==*(int*) a,b;main(i){for(;~(b=getchar());printf(" %c"+!!i,b),a|=b<<8*i++)if(i>4 s"zero"s"one"s"two"s"four"s"five"s"six"s"nine")a=i=0;} 

Using String comparison