View Compilation Error

0_0_25257625_9636.cpp: In function 'int main()':
0_0_25257625_9636.cpp:7:5: error: 'string' was not declared in this scope
     string s="HDU";
     ^
0_0_25257625_9636.cpp:10:5: error: 'cin' was not declared in this scope
     cin>>x;
     ^
0_0_25257625_9636.cpp:18:21: error: 'cout' was not declared in this scope
                     cout<<s;
                     ^
0_0_25257625_9636.cpp:18:27: error: 's' was not declared in this scope
                     cout<<s;
                           ^
0_0_25257625_9636.cpp:19:17: error: 'cout' was not declared in this scope
                 cout<<endl;
                 ^
0_0_25257625_9636.cpp:19:23: error: 'endl' was not declared in this scope
                 cout<<endl;
                       ^