foo.cpp:1:1: error: 'include' does not name a type
 include <iostream>
 ^
foo.cpp: In function 'int main()':
foo.cpp:10:1: error: 'cin' was not declared in this scope
 cin >> n >> x;
 ^
foo.cpp:18:1: error: 'cout' was not declared in this scope
 cout << ans;
 ^