/in/foo.cc: In function 'int main()':
/in/foo.cc:6:2: error: 'cin' was not declared in this scope
  cin>>n;
  ^~~
/in/foo.cc:11:3: error: 'cout' was not declared in this scope
   cout<<a[i]<<" ";
   ^~~~
/in/foo.cc:11:11: error: 'i' was not declared in this scope
   cout<<a[i]<<" ";
           ^