foo.c: In function 'main':
foo.c:22:9: warning: 'num' may be used uninitialized [-Wmaybe-uninitialized]
   22 |         printf("%d",num);
      |         ^~~~~~~~~~~~~~~~
foo.c:10:19: note: 'num' was declared here
   10 |         int k,A,B,num;
      |                   ^~~
foo.c:18:34: warning: 'B' may be used uninitialized [-Wmaybe-uninitialized]
   18 |                                 B++;
      |                                 ~^~
foo.c:10:17: note: 'B' was declared here
   10 |         int k,A,B,num;
      |                 ^
foo.c:15:34: warning: 'A' may be used uninitialized [-Wmaybe-uninitialized]
   15 |                                 A++;
      |                                 ~^~
foo.c:10:15: note: 'A' was declared here
   10 |         int k,A,B,num;
      |               ^

[Hydro](https://hydro.ac)提供评测服务