View Compilation Error

0_0_21609222_15133.cpp: In function 'int main()':
0_0_21609222_15133.cpp:13:5: error: 'cin' was not declared in this scope
     cin >> T;  
     ^
0_0_21609222_15133.cpp:17:9: error: 'cout' was not declared in this scope
         cout << a[m-n] << endl;  
         ^
0_0_21609222_15133.cpp:17:27: error: 'endl' was not declared in this scope
         cout << a[m-n] << endl;  
                           ^