def solve():
    n, m = map(int, input().split())
    if n * m % 8 != 0 or n == 1 or m == 1:
        print(-1)
        return

    rev = False
    if n % 4 == 0:
        n, m = m, n
        rev = True

    A = [[0] * m for _ in range(n)]
    c = 0

    if n % 2 == 1:
        S = [
            [1, 2, 2, 2, 5, 5, 5, 6],
            [1, 2, 3, 4, 4, 4, 5, 6],
            [1, 1, 3, 3, 3, 4, 6, 6],
        ]
        for j in range(0, m, 8):
            for i in range(3):
                for k in range(8):
                    A[i][j + k] = S[i][k] + c
            c += 6
        s = 3
    else:
        s = 0

    S = [
        [1, 1, 1, 2],
        [1, 2, 2, 2],
    ]
    for i in range(s, n, 2):
        for j in range(0, m, 4):
            for ii in range(2):
                for k in range(4):
                    A[i + ii][j + k] = S[ii][k] + c
            c += 2

    print(n * m // 4)

    if rev:
        B = [[0] * n for _ in range(m)]
        for i in range(n):
            for j in range(m):
                B[j][i] = A[i][j]

    for row in A:
        print(*row)


for _ in range(int(input())):
    solve()