为什么地板除的结果不对呢

# Enter a code

class Rational(object):

    def __init__(self,p,q):

        self.p = p

        self.q = q

    def __add__(self,r):

        return Rational(self.p*r.q + self.q*r.p,self.q*r.q)

    def __sub__(self,r):

        return Rational(self.p*r.q - self.q*r.p,self.q*r.q)

    def __mul__(self,r):

        return Rational(self.p*r.p , self.q*r.q)

    def __div__(self,r):

        return Rational(self.p*r.q,self.q*r.p)

    def __floordiv__(self,r):

        return Rational(self.p*r.q,self.q*r.p)

    def __str__(self):

        return '{}/{}'.format(self.p,self.q)

a1 = Rational(1,5)

a2 = Rational(4,5)

print(a1 + a2)

print(a1 - a2)

print(a1*a2)

print(a1/a2)

print(a1//a2)