#include <cstdio>
#include <algorithm>
using namespace std;
int v[5010];

int main()
{
    freopen("secv.in","r",stdin);
    freopen("secv.out","w",stdout);
    int n,i,j,k,sol=-1;
    scanf("%d",&n);
    int x[n],z[n];
    for(i=0;i<n;i++) {scanf("%d",&x[i]);z[i]=x[i];}
    sort(x,x+n);
    v[++v[0]]=x[0];
    for(i=1;i<n;i++) if(x[i]!=x[i-1]) v[++v[0]]=x[i];
    for(i=0;i<n;i++)
    {
        if(z[i]==v[1])
        {   k=2;
            for(j=i+1;j<n;j++)
            {
                if(z[j]==v[k]) k++;
                if(k==v[0]+1) break;
            }
            if(k==v[0]+1&&sol==-1) sol=j-i+1;
            else if(k==v[0]+1&&j-i<sol) sol=j-i+1;
        }
    }
    printf("%d",sol);
}