Merge sort with iterators

MergeSort.cpp

#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

void msort(vector<int>::iterator left, vector<int>::iterator right) {
	if (right - left <= 1) return;
	
	msort(left, left + (right - left)/2);
	msort(left + (right - left)/2, right);
	
	vector<int> res(right - left);
	merge(left, left + (right - left)/2, left + (right - left)/2, right, res.begin());

	copy(res.begin(), res.end(), left);
}

int main(int, char**) {
	vector<int> a(10);
	for (int i = 0; i < a.size(); i++) {
		a[i] = 10 - i;
		cout << a[i] << " ";
	}
	cout << endl;
	msort(a.begin(), a.end());
	for (int i = 0; i < a.size(); i++) {
		cout << a[i] << " ";
	}
	cout << endl;
	return 0;
}