#include <iostream>
#include <vector>
#include <map>

int most_frequent_element(std::vector<int> const& v)
{
    std::map<int, int> frequencyMap;
    int maxFrequency = 0;
    int mostFrequentElement = 0;
    for (int x : v)
    {
        int f = ++frequencyMap[x];
        if (f > maxFrequency)
        {
            maxFrequency = f;
            mostFrequentElement = x;
        }
    }

    return mostFrequentElement;
}

int main()
{
    std::vector<int> v { 1, 3, 5, 6, 6, 2, 3, 4, 3, 5 };
    std::cout << most_frequent_element(v);
}