#include <bits/stdc++.h>
#define int long long
#include <numeric>
using namespace std;

signed main() {
  int T, A, B;
  cin >> T >> A >> B;
  
  int ans = 0;
  ans = (T-1LL)/A + (T-1LL)/B + 1LL;
  // Tぴったりを数えないので-1、0秒の時の分を+1
  int kobai = lcm(A, B);
  kobai = (T-1)/ kobai;
  ans -= kobai;
  cout << ans << endl;
  
}