import java.util.HashMap;
import java.util.Scanner;

public class DominatedSubArray
{

    public static void main( String[] args )
    {
        Scanner s = new Scanner( System.in );
        int t = s.nextInt();
        while(t-->0)
        {
            int n = s.nextInt();
            int[] A = new int[n];
            
            for(int i=0;i<n;i++)
                A[i] =s.nextInt();
            
            System.out.println( shortestDominatedArray(A, n) );
        }
    }

    private static int shortestDominatedArray( int[] A, int n )
    {
        if(n==1)
            return -1;
        
        HashMap<Integer, String> map = new HashMap<Integer, String>();
        int minDist = Integer.MAX_VALUE;
        for(int i=0;i<n;i++)
        {
            if(!map.containsKey( A[i] ))
            {
                map.put( A[i], i+"_"+Integer.MAX_VALUE );
            }
            else
            {
                String[] value = map.get( A[i] ).split( "_" );
                int index =Integer.parseInt(value[0]);
                int dist = Integer.parseInt( value[1] );
                
                if(dist > i-index)
                    dist = i-index;
                
                String val = i+"_"+dist;
                map.put( A[i], val );
                
                if(dist<minDist)
                    minDist= dist;
            }
        }
        
        return minDist+1;
        
    }


    
}
