foo.cpp:1:1: error: 'include' does not name a type
 include <iostream>
 ^
foo.cpp: In function 'int main()':
foo.cpp:6:1: error: 'cin' was not declared in this scope
 cin>>in;
 ^
foo.cpp:17:1: error: 'cout' was not declared in this scope
 cout<<sum;
 ^