#include <iostream>
#include <vector>

int main() {
    std::vector<int> v { 1, 2, 3, 4 };
    auto it = cbegin(v);             // InputIterator
    ++it;
    ++it;
    ++it;
    std::cout << std::distance(cbegin(v), it) << std::endl;
    std::cout << std::distance(it, cend(v)) << std::endl;
}