for _ in range(int(input())):
    n, m = map(int, input().split())
    if n == 1 and m == 1:
        print("0\n1 1")
        continue
    if n % 2 == 1 or m % 2 == 1:
        print(-1)
        continue
    print(n*m - 1)
    for i in range(0, n, 2):
        t = range(0, m, 2)
        for j in (t if i % 4 == 0 else reversed(t)):
            if i % 4 == 0:
                if j == 0:
                    print(i+1, j+2)
                    print(i+2, j+1)
                else:
                    print(i+2, j+1)
                    print(i+1, j+2)
                print(i+1, j+1)
                print(i+2, j+2)
            else:
                print(i+1, j+2)
                print(i+2, j+1)
                if j == 0:
                    print(i+1, j+1)
                    print(i+2, j+2)
                else:
                    print(i+2, j+2)
                    print(i+1, j+1)