What does this page-stride loop print?

#include <cstddef>
#include <iostream>
#include <vector>

int main() {
    constexpr std::size_t page_size = 4096;
    std::vector<unsigned char> region(page_size * 4);
    std::size_t touched = 0;
    for (std::size_t offset = 0; offset < region.size(); offset += page_size) {
        region[offset] = 1;
        ++touched;
    }
    std::cout << region.size() << " " << touched << '\n';
}