def usa_to_dec(odds):
    """
    Convert international odds to American format.

    >>> usa_to_dec(-125)
    1.8
    """
    if abs(odds) < 100:
        raise Exception("Can't be less than 100.")
    if odds > 0:
        dec_odds = 1 + odds / 100
    else:
        dec_odds = 1 - 100 / odds
    return round(dec_odds, 4)
