#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

ifstream fin("secv.in");
ofstream fout("secv.out");

#define MAXN 5000

int v[MAXN + 1];
int alt[MAXN + 1];
int d[MAXN + 1];
int st[MAXN + 1];


int main()
{
    int N, i, j, o = 1, maxi, rez = -1;
    fin >> N;
    for (i = 1; i <= N; i++)
    {
        fin >> v[i];
        alt[i] = v[i];
    }
    sort(alt + 1, alt + N + 1);
    i = 1;
    while (i < N)
    {
        if (alt[i] != alt[i + 1])
        {
            o++;
        }
        i++;
    }
    for (i = 1; i <= N; i++)
    {
        j = i - 1;
        maxi = 0;
        while (j > 0)
        {
            if (v[j] < v[i])
            {
                if (maxi == 0)
                {
                    maxi = j;
                }
                else if (d[maxi] < d[j])
                {
                    maxi = j;
                }
            }
            j--;
        }
        if (maxi == 0)
        {
            st[i] = i;
            d[i] = 1;
        }
        else
        {
            d[i] = d[maxi] + 1;
            st[i] = st[maxi];
        }
    }
    for (i = 1; i <= N; i++)
    {
        if (d[i] == o)
        {
            if (rez == -1)
            {
                rez = i - st[i] + 1;
            }
            else if (rez > i - st[i] + 1)
            {
                rez = i - st[i] + 1;
            }
        }
    }
    fout << rez;
    return 0;
}