#include <fstream>
#include <algorithm>
#define MAX 5001

using namespace std;

int v[MAX], copie[MAX], subsir[MAX], pozitii[MAX];
int main()
{
    int n, m, k, i, j, l, st, dr, Min = 2e9;

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

    fin >> n;

    for(i = 1; i <= n; i++)
    {
        fin >> v[i];
        copie[i] = v[i];
    }

    sort(copie + 1, copie + 1 + n);

    subsir[1] = copie[1];

    j = 1;

    for(i = 2; i <= n; i++)
        if(copie[i] != copie[i - 1])
        {
            j++;
            subsir[j] = copie[i];
        }

    m = j;
    l = 1;

    for(i = 1; i <= n; i++)
    {
        if(v[i] == subsir[1])
        {
            pozitii[l] = i;
            l++;
        }
    }

    k = l - 1;

    for(i = 1; i <= k; i++)
    {
        l = 2;
        st = dr = pozitii[i];

        for(j = pozitii[i] + 1; j <= n && l <= m; j++)
        {
            if(v[j] == subsir[l])
            {
                dr = j;
                l++;
            }
        }

        if(l > m && Min > dr - st + 1)Min = dr - st + 1;
    }

    if(Min == 2e9)fout << -1;
    else fout << Min;

    fin.close();
    fout.close();

    return 0;
}