#include <iostream>
#include <string.h>
using namespace std;
int sum[10005];
int main()
{
    int n;
    while(cin>>n)
    {
        memset(sum,0,sizeof(sum));
        bool found=false;
        for(int i=1;i<=n;i++)
        {
            int num;
            cin>>num;
            sum[num]++;
        }
        for(int i=0;i<=10000;i++)
        {
            if(sum[i]>n/2)
            {
                found=true;
                cout<<i<<endl;
                break;
            }
        }
        if(!found)
            cout<<"-1"<<endl;
    }
    return 0;
}