def get_upper_left(row, col):
    """Returns row and col of upper left cell in block"""
    if row < 3:
        yi = 0
    elif row < 6:
        yi = 3
    else:
        yi = 6
    if col < 3:
        xi = 0
    elif col < 6:
        xi = 3
    else:
        xi = 6
    return yi, xi