#include <cstdio>
#include<algorithm>
using namespace std;
int v[5005];
int v2[5005];
int f[5005];
int main()
{
    freopen("secv.in","r",stdin);
    freopen("secv.out","w",stdout);
    int n,i,j,max=0,min=5001,k,iden,st,dr;
    scanf("%d",&n);
    for(i=1;i<=n;i++){
        scanf("%d",&v[i]);
        v2[i]=v[i];
    }
    sort(v2+1,v2+n+1);
    for(i=1;i<=n;i++)
    {
        j=1;
        iden=0;
        while(j<=n && v[i]!=v2[j]){
        if(v2[j]==v2[j+1])
          iden++;
         j++;
        }
        v[i]=j-iden;
        if(j-iden>max)
            max=j-iden;
    }
    k=1;
    for(st=dr=1;dr<=n;dr++)
    {
    if(v[dr]==k)
        k++;
    if(k==max+1)
    {
        if(dr-st<min)
            min=dr-st;
        st=dr;
    }
    }
    if(min==5001)
        printf("-1");
    else
      printf("%d",min);
    return 0;
}