View Compilation Error

0_0_31283993_7367.cpp: In function 'int main()':
0_0_31283993_7367.cpp:44:9: error: 'cout' was not declared in this scope
         cout<<n-sum/2<<endl;
         ^
0_0_31283993_7367.cpp:44:24: error: 'endl' was not declared in this scope
         cout<<n-sum/2<<endl;
                        ^