foo.c: In function 'main':
foo.c:11:9: warning: zero-length gnu_printf format string [-Wformat-zero-length]
  printf("");
         ^~
foo.c:12:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&insert);
  ^~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务