#include<fstream>
#include<algorithm>
using namespace std;
ifstream in("secv.in");
ofstream out("secv.out");
const int NMAX = 5000;
const int INF = (1 << 30);

int v[NMAX + 5],sortat[NMAX + 5],a[NMAX + 5],n,m;

void read()
{

    in>>n;
    for(int i = 1 ; i <= n ; i++)
    {
        in>>v[i];
        sortat[i] = v[i];
    }
    in.close();
}

void gaseste_subsir()
{

    sort(sortat+1,sortat+n+1);
    a[++m] = sortat[1];
    for(int i = 2 ; i <= n ; i++)
        if(sortat[i] != a[m])
            a[++m] = sortat[i];

}

int solve()
{

   int sol = INF,c;
   for(int i = 1 ; i <= n ; i++){
        c = 1;
        for(int j = i ; j <= n ; j++){
            if(v[j] == a[c])
                ++c;
            if(c == m+1)
            {
                sol = min(sol,j-i+1);
                break;
            }
        }
    }
    if(sol == INF)
        return -1;
    return sol;
}

int main()
{

    read();
    gaseste_subsir();
    out<<solve();
    return 0;
}