import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class LenaSort {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int q = in.nextInt();
        for(int a0 = 0; a0 < q; a0++){
            int len = in.nextInt();
            int c = in.nextInt();
            // your code goes here
            if(c>len*(len-1)/2)
            	System.out.println(-1);
            else
            {
            	int num[] = new int[len];
            	for(int counter=0;counter<len;counter++)
            		num[counter]=counter+1;
            	int diff=(c+1)/2;
            	
            }
            
        }
    }
}