from math import gcd
from sys import stdin

def main():
    input = lambda: stdin.readline()[:-1]
    lcm = lambda x, y: x * y // gcd(x, y)
    T, A, B = map(int, input().split())

    lcm_ = lcm(A, B)
    t = T - 1
    ans = (t // A + t // B) + 1 - t // lcm_
    print(ans)

main()