#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll gcd(ll a,ll b){
  if(b==0){
    return a;
  }
  return gcd(b,a%b);
}
int main(){
  ll t,a,b;cin >> t >> a >> b;
  ll c=a*b/gcd(a,b);
  cout << (t+a-1)/a+(t+b-1)/b-(t+c-1)/c << endl;
}