#include <fstream>

using namespace std;

ifstream in("elmaj.in");
ofstream out("elmaj.out");

int i, n, ap, e, x;

int main()
{
    in >> n >> x;
    e=x;
    ap=1;
    for(int i=2;i<=n;i++)
    {
        in >> x;
        if(e==x)
            ap++;
        else
            ap--;
        if(ap==0)
        {
            e=x;
            ap=1;
        }
    }
    if(ap<=0)
        out << -1;
    else
    {
        ap = 0;
        in.close();
        ifstream in("elmaj.in");
        for(i=1;i<=n;i++)
        {
            in >> x;
            if(x==e)
                ap++;
        }
         if(ap>=n/2+1)
            out << e << ap;
        else
            out << -1;
    }
    in.close();
    out.close();
    return 0;
}