View Compilation Error

0_0_18230715_2317.cpp:1:1: error: 'include' does not name a type
 include <iostream>
 ^
0_0_18230715_2317.cpp: In function 'int main()':
0_0_18230715_2317.cpp:10:5: error: 'cin' was not declared in this scope
     cin >> n >> L >> g;
     ^
0_0_18230715_2317.cpp:14:5: error: 'cout' was not declared in this scope
     cout << ans << endl;
     ^
0_0_18230715_2317.cpp:14:20: error: 'endl' was not declared in this scope
     cout << ans << endl;
                    ^