View Compilation Error

0_0_21439839_15654.cpp: In function 'int main()':
0_0_21439839_15654.cpp:5:5: error: 'cin' was not declared in this scope
     cin >> T;  
     ^
0_0_21439839_15654.cpp:19:9: error: 'cout' was not declared in this scope
         cout << sum << endl;  
         ^
0_0_21439839_15654.cpp:19:24: error: 'endl' was not declared in this scope
         cout << sum << endl;  
                        ^