"""

奇数だと無理？


"""

import sys
import heapq
from collections import deque
from sys import stdin

TT = int(stdin.readline())

for i in range(TT):

    N,M = map(int,stdin.readline().split())

    if N == M == 1:
        print (0)
        print (1,1)
        continue

    elif N % 2 == 1 or M % 2 == 1:
        print (-1)
        continue

    print (N*M-1)

    ans = []

    x,y = 1,1

    for loop in range(M//2 + 2):

        for i in range(N//2-1):
            
            ans.append((x,y))
            
            x += 1 ; y += 1
            ans.append((x,y))
            
            x -= 1 ;
            ans.append((x,y))
            
            y -= 1 ; x += 1
            ans.append((x,y))

            x += 1


        ans.append((x,y))

        x += 1 ; y += 1
        ans.append((x,y))

        y -= 1
        ans.append((x,y))

        x -= 1 ; y += 1
        ans.append((x,y))

        y += 1


        ans.append((x,y))

        x += 1 ; y += 1
        ans.append((x,y))

        y -= 1
        ans.append((x,y))

        x -= 1 ; y += 1
        ans.append((x,y))

        x -= 1


        for i in range(N//2-1):
            
            ans.append((x,y))
            
            x -= 1 ; y -= 1
            ans.append((x,y))
            
            x += 1 ;
            ans.append((x,y))
            
            y += 1 ; x -= 1
            ans.append((x,y))

            x -= 1

        x += 1
        y += 1

    pl = [ [None]*N for i in range(M) ]
    for i in range(N*M):
        print (*ans[i])
        pl[ans[i][1]-1][ans[i][0]-1] = i

    for i in pl:
        pass
        #print (i)