# [C (clang)], 133 bytes

<!-- language-all: lang-c -->

 N,d,y,x,a[9],o;f(*s){sscanf(s," %[0-9N] %c %d = %d",a,&o,&y,&x);d=!sscanf(a,"%d",&d)?1:d;N=(x-(o>43?-y:y))*2/d;printf("%d",N/2+N%2);}

[Try it online!][TIO-jg4renoe]

[C (clang)]: http://clang.llvm.org/
[TIO-jg4renoe]: https://tio.run/##bY/vboIwFMW/9ynuukBabMcfYYsy9A14AeOHppVJwsBQSCDGZ2eATtDYD@3N75x7ciq5zET@072nucxqdYBvXam0@Dhuupgp1rKGid1qz4owIZamZ62lyBOiGQZj5/BVvAdDgqEg6i/MBDMLZrbMbGioorebWzA8iKaiW3etwjgiDSfFxl9uebtuKbU8W4WnMs2rhIzO2PYWseHR8NJJkWUJkUdRglVJCnBGcLdquB3O@QYAM@gtIYKEXN9TXWmCcT9eEOp34FekOaFDxjUXQwwLcPv2y8E1o3ykwZx6L7136s/p8p@6D@ZgwMEQ4cyx@@Xcs313UFB5qOoyB2esbltoKvrwZw9NXR@ET@S93nBhUvynLMtG3R8 "C (clang) – Try It Online"

This handles all spaces except between `d` and `N`. 

[Removed wrong answer that rounds down]