/in/foo.cc:1:1: error: 'n' does not name a type
 n=int(input())
 ^
/in/foo.cc:9:1: error: 'a' does not name a type
 a[1]=1;
 ^
/in/foo.cc:10:1: error: expected unqualified-id before 'for'
 for i in range(2,n):
 ^~~