#include <bits/stdc++.h>
using namespace std;

#include <atcoder/all>
using namespace atcoder;

using ll = long long;
using mint = modint998244353;

int main() {
  ll N, A, B;
  cin >> N >> A >> B;
  ll a = N / A;
  ll b = N / B;
  ll ab = N / lcm(A, B);
  cout << N - a - b + ab << endl;
}