View Compilation Error

0_0_30477110_31545.cpp: In function 'int main()':
0_0_30477110_31545.cpp:11:9: error: 'cin' was not declared in this scope
   while(cin>>n)
         ^
0_0_30477110_31545.cpp:30:4: error: 'cout' was not declared in this scope
    cout<<num<<endl;
    ^
0_0_30477110_31545.cpp:30:15: error: 'endl' was not declared in this scope
    cout<<num<<endl;
               ^