/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author Namila
 */


 import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
public class lena {
    
   



    public static void main(String[] args) {
       
        
        Scanner in = new Scanner(System.in);
        int q = in.nextInt();
        for(int a0 = 0; a0 < q; a0++){
            int x=0;int t;
            int len = in.nextInt();
            int c = in.nextInt();
           int ar[]=new int[len];
           
           for(t=0;t<len;t++){
            t++;   
           }
            // your code goes here
          if (c>t){
              System.out.println("-1");
          }
          else{
           for(int i=1;i<=len;i++){
               ar[i]=c-x;
               x++;
           }
              
              
              
              
          }
            
            
            
            
            
            
        }
        
        
        
        
        
    }
}