#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
  long long n, a, b;
  cin >> n >> a >> b;
  long long ans = 0;
  ans = n - (n / a) - (n / b) + (n / (a / __gcd(a, b) * b));
  cout << ans << endl;
}