What does this log?

1#include <iostream>
2 
3struct Handler {
4  virtual int handle(int x) { return x; }
5};
6struct Doubler : Handler {
7  int handle(int x) override { return x * 2; }
8};
9int main() {
10    Handler* h = new Doubler();
11    std::cout << h->handle(21) << "\n";
12    delete h;
13}