def gcd(a, b):
    if a < b:
        a, b = b, a
    while b >= 1:
        a, b = b, a % b
    return a


def lcm(a, b):
    return a * b // gcd(a, b)


t, a, b = [int(v) for v in input().split()]
c = lcm(a, b)
print( (t+a-1)//a + (t+b-1)//b - (t+c-1)//c)