import java.awt.*;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;
import static java.lang.Math.*;
public class Main{
    static int count(String s){
        int c=0;
        for (int i=0;i<s.length();i++){
            if (s.charAt(i)=='1')c++;
        }
        return c;
    }
    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
//        Scanner sc= new Scanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        int t=sc.nextInt();
        outer:while (t-->=1) {
            int n=sc.nextInt();
            int a[]=sc.readArray(n);
            int fre[]= new int[n+1];
            for (int i=0;i<n;i++){
                fre[a[i]]++;
            }
            int maxFre=Integer.MIN_VALUE;
            int maxElement=0;
            for (int i=0;i<n;i++){
                if (maxFre<fre[i]){
                    maxFre=fre[i];
                    maxElement=i;
                }
            }
//            int count=0;
//
//            for (int i=0;i<n;i++){
//                if (maxFre==fre[i])count++;
//            }
//            if (count>1){
//                System.out.println(-1);
//                continue outer;
//            }
            if (n==1){
                System.out.println(-1);
                continue outer;
            }
            ArrayList<Integer> list = new ArrayList<>();
            for (int i=0;i<n;i++){
                if (maxElement==a[i]){
                    list.add((i+1));
                }
            }
            int min=Integer.MAX_VALUE;

            for (int i=1;i<list.size();i++){
                int v=list.get(i)-(list.get(i-1)-1);

                min=min(min,v);

            }
            System.out.println(min);

        }

        out.flush();

    }
    //-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

    static void sort(int[] a) {
        ArrayList<Integer> l=new ArrayList<>();
        for (int i:a) l.add(i);
        Collections.sort(l);
        for (int i=0; i<a.length; i++) a[i]=l.get(i);
    }
    static String sortString(String s){
        char temp[]=s.toCharArray();
        Arrays.sort(temp);
        return new String(temp);
    }

    static class Pair implements Comparable<Pair> {
        int a, b;

        public Pair(int a, int b) {
            this.a = a;
            this.b = b;
        }
        public int compareTo(Pair other){
            if(this.a==other.a) return other.b>this.b?-1:1;
            else if(this.a>other.a) return 1;
            else return -1;
    }

    }
    static int mod=(int)1e9+7;
    static long mod(long x){
        return ((x%mod+mod)%mod);
    }
    static long add(long x,long y){
        return mod(mod(x)+mod(y));
    }
    static long mul(long x,long y){
        return mod(mod(x)*mod(y));
    }
    static int[] find(int n,int start,int diff){
        int a[]= new int[n];
        a[0]=start;
        for (int i=1;i<n;i++)a[i]=a[i-1]+diff;
        return a;
    }
    static void swap(int a,int b){
        int c=a;
        a=b;
        b=c;
    }

    static void printArray(int a[]){
        for (int i=0;i<a.length;i++){
            System.out.print(a[i]+" ");
        }
    }
    static boolean sorted(int a[]){
        int n=a.length;
        boolean flag=true;
        for (int i=0;i<n-1;i++){
            if (a[i]>a[i+1])flag=false;
        }
        if (flag)return true;
        else  return false;
    }
    public static int findlog(long n){
        if(n == 0)
            return 0;

        if(n == 1)
            return 0;
        if(n == 2)
            return 1;
        double num = Math.log(n);
        double den = Math.log(2);
        if(den == 0)
            return 0;
        return (int)(num/den);
    }
    public static long gcd(long a,long b){
        if(b%a == 0)
            return a;
        return gcd(b%a,a);
    }
    public static int gcdInt(int a,int b){

        if(b%a == 0)
            return a;

        return gcdInt(b%a,a);

    }

    static void sortReverse(long[] a) {
        ArrayList<Long> l=new ArrayList<>();
        for (long i:a) l.add(i);
//        Collections.sort.(l);
        Collections.sort(l,Collections.reverseOrder());
        for (int i=0; i<a.length; i++) a[i]=l.get(i);
    }

    static class FastScanner {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer("");
        String next() {
            while (!st.hasMoreTokens())
                try {
                    st=new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }
        int[] readArray(int n) {
            int[] a=new int[n];
            for (int i=0; i<n; i++) a[i]=nextInt();
            return a;
        }
        long[] readArrayLong(long n) {
            long[] a=new long[(int)n];
            for (int i=0; i<n; i++) a[i]=nextLong();
            return a;
        }
        long nextLong() {
            return Long.parseLong(next());
        }
    }


}