#include <bits/stdc++.h>

using namespace std;

FILE* si=fopen("secv.in","r");
FILE* so=fopen("secv.out","w");

int n,i,j,k,rasp,ok,x,v[5001],v2[4001];

int main()
{
    fscanf(si,"%d",&n);
    for(i=1; i<=n; i++)
    {
        fscanf(si,"%d",&v[i]);
        v2[i]=v[i];
    }
    sort(v2+1,v2+n+1);
    k=1;
    for(i=2; i<=n; i++)
        if(v2[i]!=v2[k])
            v2[++k]=v2[i];
    rasp=2000000001;
    ok=0;
    for(i=1; i<=n; i++)
    {
        x=1;
        for(j=i; j<=n; j++)
        {
            if(v[j]==v2[x])
                x++;
            if(x>k)
            {
                ok=1;
                rasp=min(rasp,j-i+1);
                break;
            }
        }
    }
    if(ok==0)
        fprintf(so,"-1");
    else
        fprintf(so,"%d",rasp);

    fclose(si);
    fclose(so);

    return 0;
}