/* -*- coding: utf-8 -*-
 *
 * 3152.cc:  No.3152 neither multiple of A nor B  - yukicoder
 */

#include<cstdio>
#include<algorithm>
#include<numeric>

using namespace std;

/* typedef */

using ll = long long;

/* main */

int main() {
  ll n, a, b;
  scanf("%lld%lld%lld", &n, &a, &b);
  
  ll g = gcd(a, b), l = a * b / g;
  ll x = n - n / a - n / b + n / l;

  printf("%lld\n", x);
  
  return 0;
}