#!/usr/bin/env python3

import math


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


def solve(t, a, b):
    num_a = (t - 1) // a
    num_b = (t - 1) // b
    num_ab = (t - 1) // lcm(a, b)
    return 1 + num_a + num_b - num_ab


def main():
    t, a, b = (int(z) for z in input().split())
    res = solve(t, a, b)
    print(res)


if __name__ == "__main__":
    main()