foo.c: In function ‘main’:
foo.c:50:9: warning: implicit declaration of function ‘scanf’ [-Wimplicit-function-declaration]
   50 |         scanf("%d", &x);
      |         ^~~~~
foo.c:1:1: note: include ‘<stdio.h>’ or provide a declaration of ‘scanf’
  +++ |+#include <stdio.h>
    1 | int sh(int n)
foo.c:50:9: warning: incompatible implicit declaration of built-in function ‘scanf’ [-Wbuiltin-declaration-mismatch]
   50 |         scanf("%d", &x);
      |         ^~~~~
foo.c:50:9: note: include ‘<stdio.h>’ or provide a declaration of ‘scanf’
foo.c:52:17: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
   52 |                 printf("Yes");
      |                 ^~~~~~
foo.c:52:17: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
foo.c:52:17: warning: incompatible implicit declaration of built-in function ‘printf’ [-Wbuiltin-declaration-mismatch]
foo.c:52:17: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’
foo.c:54:17: warning: incompatible implicit declaration of built-in function ‘printf’ [-Wbuiltin-declaration-mismatch]
   54 |                 printf("No");
      |                 ^~~~~~
foo.c:54:17: note: include ‘<stdio.h>’ or provide a declaration of ‘printf’