View Compilation Error

0_0_17078579_32162.cpp: In function 'int main()':
0_0_17078579_32162.cpp:18:7: error: 'cin' was not declared in this scope
 while(cin >> n) {
       ^
0_0_17078579_32162.cpp:19:1: error: 'cout' was not declared in this scope
 cout << vec[n] << endl;
 ^
0_0_17078579_32162.cpp:19:19: error: 'endl' was not declared in this scope
 cout << vec[n] << endl;
                   ^