#include<iostream>
#include<algorithm>
#include<cmath>
#include<iomanip>
#include<vector>
#include<map>
#include<queue>
using namespace std;
typedef long long ll;
const int MOD=1e9+7;
int main() {
  ll a,b,t,g,ans=1;
  cin >> t >> a >> b;
  g=__gcd(a,b);
  ans+=(t-1)/a+(t-1)/b;
  unsigned long long l=a/g*b;
  ans-=(t-1)/l;
  cout << ans << endl;
}