#include <iostream>
#include <algorithm>
using namespace std;
typedef long long ll;

ll gcd(ll a,ll b);

int main(void){
  ll t,a,b,lcm,ans;
  cin >> t >> a >> b;
  lcm=a*b/gcd(a,b);
  ans=(t-1)/a+(t-1)/b+1;
  if (lcm>0) ans-=(t-1)/lcm;
  cout << ans << endl;
  return 0;
}

ll gcd(ll a,ll b){
  if (a>b) swap(a,b);
  if (a==0) return b;
  return gcd(b%a,a);
}