What does this C++ snippet output?

1#include <iostream>
2#include <vector>
3#include <algorithm>
4int main() {
5    std::vector<int> v = {1, 2, 3, 4, 5};
6    int sum = 0;
7    std::for_each(v.begin(), v.end(), [&sum](int x) { sum += x; });
8    std::cout << sum << "\n";
9}