View Compilation Error

0_0_39478518_20855.cpp: In function 'int calctail(int, int)':
0_0_39478518_20855.cpp:7:41: error: 'cout' was not declared in this scope
    7 |                                         cout <<'0'<< i << ' ';
      |                                         ^~~~
0_0_39478518_20855.cpp:10:41: error: 'cout' was not declared in this scope
   10 |                                         cout << i << ' ';
      |                                         ^~~~
0_0_39478518_20855.cpp: In function 'int main()':
0_0_39478518_20855.cpp:20:24: error: 'cin' was not declared in this scope
   20 |                 while (cin >> a >> b) {
      |                        ^~~