for _ in range(int(input())):
	N, M = map(int, input().split())
	if N * M % 4 != 0:
		print(-1)
	elif N % 4 == 0:
		if M % 2 == 0:
			K = N * M // 4
			print(K)
			ans = [[0] * M for _ in range(N)]
			c = 1
			for i in range(N // 4):
				for j in range(M // 2):
					ans[4 * i][2 * j] = c
					ans[4 * i][2 * j + 1] = c
					ans[4 * i + 1][2 * j] = c
					ans[4 * i + 1][2 * j + 1] = c + 1
					ans[4 * i + 2][2 * j] = c
					ans[4 * i + 2][2 * j + 1] = c + 1
					ans[4 * i + 3][2 * j] = c + 1
					ans[4 * i + 3][2 * j + 1] = c + 1
					c += 2
			for i in range(N):
				print(*ans[i])
		else:
			print(-1)
	elif N % 2 == 0:
		if M % 4 == 0:
			K = N * M // 4
			print(K)
			ans = [[0] * M for _ in range(N)]
			c = 1
			for i in range(N // 2):
				for j in range(M // 4):
					ans[2 * i][4 * j] = c
					ans[2 * i + 1][4 * j] = c
					ans[2 * i][4 * j + 1] = c
					ans[2 * i + 1][4 * j + 1] = c + 1
					ans[2 * i][4 * j + 2] = c
					ans[2 * i + 1][4 * j + 2] = c + 1
					ans[2 * i][4 * j + 3] = c + 1
					ans[2 * i + 1][4 * j + 3] = c + 1
					c += 2
			for i in range(N):
				print(*ans[i])
		else:
			print(-1)
	else:
		print(-1)