foo.c: In function 'main':
foo.c:5:20: warning: unused variable 'k' [-Wunused-variable]
   int a[10000],n,i,k,x;
                    ^
foo.c:6:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&n);
   ^~~~~~~~~~~~~~
foo.c:8:4: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d",&a[i]);
    ^~~~~~~~~~~~~~~~~
foo.c:9:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&x);
   ^~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务