/in/foo.c: In function 'main':
/in/foo.c:4:5: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    4 |     scanf("%d%d",&a,&b);
      |     ^~~~~
/in/foo.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | int main()
/in/foo.c:4:5: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
    4 |     scanf("%d%d",&a,&b);
      |     ^~~~~
/in/foo.c:4:5: note: include '<stdio.h>' or provide a declaration of 'scanf'
/in/foo.c:6:5: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    6 |     printf("%d\n",c);
      |     ^~~~~~
/in/foo.c:6:5: note: include '<stdio.h>' or provide a declaration of 'printf'
/in/foo.c:6:5: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
/in/foo.c:6:5: note: include '<stdio.h>' or provide a declaration of 'printf'