#include <bits/stdc++.h>
using namespace std;
ifstream in("secv.in");
ofstream out("secv.out");
const int N = 5005;
int v[N],dp[N],lst[N];
int main()
{
    int n;
    in >> n;
    for (int i = 1; i<=n; i++)
    {
        in >> v[i];
        lst[i] = v[i];
    }
    int k = 0;
    sort(lst+1,lst+n+1);
    for (int i = 1; i<=n; i++)
        if (lst[i]!=lst[k])
            lst[++k] = lst[i];
    int ans = INT_MAX;
    bool ok = 0;
    for (int i = 1; i<=n; i++)
    {
        int el = 1, j;
        for (j = i; j<=n; j++)
            if (v[j] == lst[el])
            {
                el++;
                if (el>k)
                    break;
            }
        if (el>k)
        {
            ok = 1;
            ans = min(ans,j-i+1);
        }
    }
    if (!ok)
        out << -1;
    else
        out << ans;
}