foo.c: In function 'main':
foo.c:20:6: warning: unused variable 'i' [-Wunused-variable]
   20 |  int i,n,a[9999];
      |      ^
foo.c: In function 'fun':
foo.c:7:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    7 |   scanf("%d",&a[i]);
      |   ^~~~~~~~~~~~~~~~~
foo.c:9:1: warning: control reaches end of non-void function [-Wreturn-type]
    9 | }
      | ^
foo.c: In function 'Output':
foo.c:17:1: warning: control reaches end of non-void function [-Wreturn-type]
   17 | }
      | ^
foo.c: In function 'main':
foo.c:21:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   21 |  scanf("%d",&n);
      |  ^~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务