foo.c: In function 'a':
foo.c:14:2: warning: this 'else' clause does not guard... [-Wmisleading-indentation]
  else
  ^~~~
foo.c:16:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'else'
   return end;
   ^~~~~~
foo.c: In function 'main':
foo.c:22:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ^~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务