n = 10
i, j = 0, 0
going_down = True
for k in range(n):
    print("({}, {})".format(i, j))
    if going_down:
        if j == 0:
            going_down = False
            i += 1
        else:
            i += 1
            j -= 1
    else:
        if i == 0:
            going_down = True
            j += 1
        else:
            i -= 1
            j += 1