View Compilation Error

0_0_27358292_32060.cpp: In function 'int main()':
0_0_27358292_32060.cpp:6:5: error: 'cin' was not declared in this scope
     cin>>n;
     ^
0_0_27358292_32060.cpp:9:21: error: 'scanf' was not declared in this scope
         scanf("%s",a);
                     ^
0_0_27358292_32060.cpp:13:9: error: 'cout' was not declared in this scope
         cout<<sum<<endl;
         ^
0_0_27358292_32060.cpp:13:20: error: 'endl' was not declared in this scope
         cout<<sum<<endl;
                    ^