#include<iostream>
#include<cstdio>
#include<algorithm>
#include<queue>
#include<map>
#include<cstring>
#include<stdlib.h>
#include<vector>
#include<stack>
#include<math.h>
#define LL long long
#define inf (0x3f3f3f3f)
#define mod (1000000007)
using namespace std;


int main()
{
    int vis[10005];
    int n;
    while (scanf("%d", &n) != EOF)
    {
        memset(vis, 0, sizeof(vis));
        int x;
        for (int i = 1; i <= n; i++)
        {
            scanf("%d", &x);
            vis[x]++;
        }
        int flag = 1;
        for (int i = 1; i < 10000; i++)
        {
            if (vis[i] > n / 2)
            {    
                flag = 0;
                printf("%d\n", i);
                break;
            }
        }
        if (flag) printf("-1\n");
    }
    return 0;
}