foo.c: In function 'mian':
foo.c:17:14: error: 'a' undeclared (first use in this function)
   17 |  scanf("%d",&a[i]);
      |              ^
foo.c:17:14: note: each undeclared identifier is reported only once for each function it appears in
foo.c:17:16: error: 'i' undeclared (first use in this function)
   17 |  scanf("%d",&a[i]);
      |                ^

[Hydro](https://hydro.ac)提供评测服务