Порядок

#define _USE_MATH_DEFINES
#include <iostream>
#include <conio.h>
#include <string>
#include <set>
#include <map>
#include <algorithm>
#include <string>
#include <math.h>
#include <vector>
#include <cmath>

using namespace std;

long long n, k[500001], prom, prom2, maxan;

int main()
{
    long long max;
    max = 0;
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> k[i];

    sort(k + 1, k + n + 1);

    prom = k[1];
    prom2 = 1;
    maxan = prom;
    for (int i = 2; i <= n; i++)
        if (k[i] != prom)
        {
            if (prom2 > max)
            {
                maxan = prom;
                max = prom2;
            }
            prom = k[i];
            prom2 = 1;
        }
        else
            prom2++;

    if (prom2 > max)
    {
        maxan = prom;
        max = prom2;
    }

    cout << maxan;
    _getch();
    return 0;
}