#include <fstream>
#include <algorithm>

using namespace std;

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

int d[5001],v[5001],i,j,mins,n,nr,x,w[5001],k,ok,okf,s;

int main()
{
    f>>n;
    for(i=1;i<=n;i++){
        f>>v[i];
        d[i]=1;
        w[i]=v[i];
    }
    sort(w+1,w+n+1);
    k=1;
    for(i=2;i<=n;i++)
        if(w[i]!=w[k])
            w[++k]=w[i];
    mins=n+1;
    for(i=1;i<=n;i++)
        if(v[i]==w[1]){
            ok=1;
        for(j=i,x=1;j<=n;j++)
            if(v[j]==w[x]){
                x++;
                if(x==k+1){
                ok=0;
                break;
                }
            }
            if(ok==0){
                okf=1;
                s=j-i+1;
                if(s<mins)
                    mins=s;
            }
        }
        if(okf==1)
            g<<mins;
        else
            g<<"-1";
    return 0;
}