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

int main() {
  int64_t T, A, B;
  cin >> T >> A >> B;

  int64_t g = __gcd(A, B);
  if (1.0 * A * B / g < T) {
    int64_t x = A / g * B;
    cout << (1 + (T - 1) / A) + (1 + (T - 1) / B) - (1 + (T - 1) / x) << endl;
  } else {
    cout << (1 + (T - 1) / A) + (1 + (T - 1) / B) - 1 << endl;
  }

  return 0;
}