import math

def lcm(x, y):
    return (x * y) // math.gcd(x, y)

t, a, b = map(int, input().split())
A = int((t - 1) // a)
B = int((t - 1) // b)
C = int((t - 1) // lcm(a, b))
print(A + B - C + 1)