/in/foo.c: In function 'main':
/in/foo.c:22:2: warning: 'num' may be used uninitialized in this function [-Wmaybe-uninitialized]
  printf("%d",num);
  ^~~~~~~~~~~~~~~~
/in/foo.c:18:6: warning: 'B' may be used uninitialized in this function [-Wmaybe-uninitialized]
     B++;
     ~^~
/in/foo.c:19:5: warning: 'A' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if(A==B)
     ^