foo.c: In function 'main':
foo.c:5:9: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    5 |         scanf("%d %d", &n, &m);
      |         ^~~~~
foo.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | int main()
foo.c:5:9: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    5 |         scanf("%d %d", &n, &m);
      |         ^~~~~
foo.c:5:9: note: include '<stdio.h>' or provide a declaration of 'scanf'
foo.c:20:33: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
   20 |                                 printf("%d", cnt);
      |                                 ^~~~~~
foo.c:20:33: note: include '<stdio.h>' or provide a declaration of 'printf'
foo.c:20:33: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
foo.c:20:33: note: include '<stdio.h>' or provide a declaration of 'printf'
foo.c:24:33: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   24 |                                 printf("%d", -1);
      |                                 ^~~~~~
foo.c:24:33: note: include '<stdio.h>' or provide a declaration of 'printf'
foo.c:29:17: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   29 |                 printf("%d", -1);
      |                 ^~~~~~
foo.c:29:17: note: include '<stdio.h>' or provide a declaration of 'printf'

[Hydro](https://hydro.ac)提供评测服务