Online C++ compiler: run C++ and the STL in your browser

#include <iostream>
using namespace std;

int main() {
    cout << "Hello, world!\n";
    cout << "Learn to code\n";
    cout << "by playing.\n";
    for (int n = 1; n <= 3; n++) {
        cout << "Level " << n;
        cout << " unlocked!\n";
    }
}