View Compilation Error

0_0_38515129_19530.cpp: In function 'int main()':
0_0_38515129_19530.cpp:4:12: error: 'cin' was not declared in this scope
     while (cin >> a)
            ^
0_0_38515129_19530.cpp:9:13: error: 'cout' was not declared in this scope
             cout << "Case" << t <<":" << '\n' << endl;
             ^
0_0_38515129_19530.cpp:9:50: error: 'endl' was not declared in this scope
             cout << "Case" << t <<":" << '\n' << endl;
                                                  ^