using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var t = NN;
        var ans = new string[t];
        for (var u = 0; u < t; ++u)
        {
            var c = NList;
            ans[u] = Bis(c[0], c[1]);
        }
        WriteLine(string.Join("\n", ans));
    }
    static string Bis(int h, int w)
    {
        if (h == 1 && w == 1) return "0\n1 1";
        if (h % 2 == 1 || w % 2 == 1) return "-1";
        var t = new System.Text.StringBuilder();
        var ans = new List<string>();
        ans.Add((h * w - 1).ToString());
        var x = 0;
        var y = 1;
        var mx4 = new int[] { 1, 1, -1, 1 };
        var my4 = new int[] { 0, 1, 0, -1 };
        if (w == 2)
        {
            for (var i = 0; i < h * w; ++i)
            {
                x += mx4[i % 4];
                y += my4[i % 4];
                ans.Add($"{x} {y}");
            }
            return string.Join("\n", ans);
        }
        var mx1 = new int[] { 1, 1, 0, -1 };
        var my1 = new int[] { 0, 1, -1, 1 };
        var mx2 = new int[] { 0, 1, 0, -1 };
        var my2 = new int[] { 1, 1, -1, 1 };
        var mx3 = new int[] { 0, 1, -1, 1 };
        var my3 = new int[] { 1, 1, 0, -1 };
        var mx5 = new int[] { 0, -1, 0, 1 };
        var my5 = new int[] { -1, -1, 1, -1 };
        for (var i = 0; i < h; i += 2)
        {
            if (i % 4 == 0)
            {
                for (var j = 0; j < w; j += 2)
                {
                    for (var p = 0; p < 4; ++p)
                    {
                        if (j == 0)
                        {
                            x += mx1[p];
                            y += my1[p];
                        }
                        else if (j + 2 < w)
                        {
                            x += mx2[p];
                            y += my2[p];
                        }
                        else
                        {
                            x += mx3[p];
                            y += my3[p];
                        }
                        ans.Add($"{x} {y}");
                    }
                }
            }
            else
            {
                for (var j = w - 2; j >= 0; j -= 2)
                {
                    for (var p = 0; p < 4; ++p)
                    {
                        if (j + 2 == w)
                        {
                            x += mx4[p];
                            y += my4[p];
                        }
                        else
                        {
                            x += mx5[p];
                            y += my5[p];
                        }
                        ans.Add($"{x} {y}");
                    }
                }
            }
        }
        return string.Join("\n", ans);
    }
}