#include<iostream>

#include<cstdio>

#include<cstdlib>

#include<cstring>

#include<string>

#define ll long long

using namespace std;

int T,n,ans;

int a[],nxt[],hd[];

int main()

{

    scanf("%d",&T);

    while(T--)

    {

      for(int i=;i<=n;i++)hd[i]=nxt[i]=;

      scanf("%d",&n);

      for(int i=;i<=n;i++){scanf("%d",&a[i]);nxt[i]=hd[a[i]];hd[a[i]]=i;}

      ans=1e9;

      for(int i=;i<=n;i++)if(nxt[i])ans=min(ans,i-nxt[i]+);

      printf(ans==1e9?"-1\n":"%d\n",ans);

    }

    return ;

}