foo.c: In function 'main':
foo.c:10:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   10 |  for(i=2;i<=num-1&&flag;i++)
      |  ^~~
foo.c:13:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   13 |   for(j=2;j<=num;j++)
      |   ^~~
foo.c:4:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    4 |  scanf("%d",&num);
      |  ^~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务