#include <cstdio>
#include <algorithm>

int a[501],b[501],c[501];

int main()
{
    int n,i,cnt,l,j,k,min;
    freopen("secv.in","r",stdin);
    freopen("secv.out","w",stdout);
    scanf("%d", &n);
    for (i=1;i<=n;i++)
        scanf("%d", &a[i]),b[i]=a[i];
    std::sort(b+1,b+n+1);
    k=1;
    c[1]=b[1];
    for (i=2;i<=n;i++)
        if (b[i]!=c[k])
            c[++k]=b[i];
    min=(1<<31)-1;
    for (i=1;i<=n;i++) {
        if (a[i]==c[1]) {
            cnt=2;
            l=1;
            for (j=i+1;j<=n;j++) {
                l++;
                if (a[j]==c[cnt])
                    cnt++;
                if (cnt-1==k) {
                    if (l<min)
                        min=l;
                    break;
                }
            }
        }
    }
    if (min==(1<<31)-1)
        printf("%d\n",-1);
    else
        printf("%d\n", min);
    return 0;
}