foo.c: In function 'main':
foo.c:9:9: warning: zero-length gnu_printf format string [-Wformat-zero-length]
  printf("");
         ^~
foo.c:10:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&insert1,&insert2);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务