/in/foo.c: In function 'main':
/in/foo.c:4:5: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
     scanf("%d", &n);
     ^~~~~
/in/foo.c:4:5: warning: incompatible implicit declaration of built-in function 'scanf'
/in/foo.c:4:5: note: include '<stdio.h>' or provide a declaration of 'scanf'
/in/foo.c:13:9: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
         printf("%d %d\n", new_ci, new_ei);
         ^~~~~~
/in/foo.c:13:9: warning: incompatible implicit declaration of built-in function 'printf'
/in/foo.c:13:9: note: include '<stdio.h>' or provide a declaration of 'printf'
/in/foo.c:15:9: warning: incompatible implicit declaration of built-in function 'printf'
         printf("00\n");
         ^~~~~~
/in/foo.c:15:9: note: include '<stdio.h>' or provide a declaration of 'printf'