View Compilation Error

0_0_28914760_29562.cpp: In function 'int main()':
0_0_28914760_29562.cpp:30:2: error: 'cin' was not declared in this scope
  cin>>n;
  ^
0_0_28914760_29562.cpp:32:2: error: 'cout' was not declared in this scope
  cout<<ans<<endl;
  ^
0_0_28914760_29562.cpp:32:13: error: 'endl' was not declared in this scope
  cout<<ans<<endl;
             ^