#include <iostream>
#include <algorithm>
#include <fstream>
using namespace std;
long long maxim, i, v[5005], y[5005], ap[5005], m, l, lmin, n, j;
int main()
{
    ifstream cin("secv.in");
    ofstream cout("secv.out");
    cin>>n;lmin=n;
    for(i=1; i<=n; i++)
        cin>>v[i], y[i]=v[i];
    sort(y+1,y+n+1);
    for(i=2; i<=n+1; i++)
    if(y[i]!=y[i-1])
    ap[++m]=y[i-1];
    for(i=1; i<=n; i++)
    if(v[i]==ap[1])
    {l=1;
    for(j=i+1; j<=n; j++){
    if(v[j]==ap[l+1])
    l++;
    if(m==l)
    if(j-i+1<lmin){
    lmin=j-i+1;break;}
    }
    }
    if(n==lmin)
    cout<<-1<<'\n';
    else
    cout<<lmin<<'\n';
    return 0;
}