#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#define N 256
int comp(const void*a, const void*b)
{
    return *((int *)a) - *((int *)b);
}
int find_kth_num(int nums[N], int length, int k)
{
    int counts[1001];
    int sum = 0;
    int i;
    memset(counts, 0, 1001 * sizeof(int));
    qsort(nums, length, sizeof(int), comp);
    for (i = 0; i < length; i++)
    {
        sum += (counts[nums[i]] == 0);
        counts[nums[i]] = 1;
        if (sum == k)
        {
            return nums[i];
        }
    }
    return -1;
}
int main()
{
    int n = 0;
    int i;
    int nums[N];
    scanf("%d", &n);
    for (i = 0; i < n; i++)
    {
        scanf("%d", nums + i);
    }
    printf("%d", find_kth_num(nums, n, 3));
    return 0;
}