#include <bits/stdc++.h>

using namespace std;

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

int a[5001];

int main()
{
    int n;
    in >> n;

    for (int i=1; i<=n; i++)
        {
            in >> a[i];
        }

    vector<int>aux;
    for (int i=1; i<=n; i++)
        aux.push_back(a[i]);
    sort(aux.begin(), aux.end());
    vector<int>uni;
    uni.push_back(aux[0]);
    for (int x : aux)
    {
        if (uni.back() != x)
            uni.push_back(x);
    }

    int ans = n+1;

    for (int i=1; i<=n; i++)
    {
        int pos = 0;

        for (int j=i; j<=n; j++)
        {
            if (a[j] == uni[pos])
                pos++;
            if (pos == uni.size())
                {
                    ans = min(ans, j-i+1);
                    break;
                }
        }
    }

    if (ans > n)
        out << -1;
    else
        out << ans;

    return 0;
}