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

int main()
{
	long long n, a, b;
	cin >> n >> a >> b;
	
	long long p = n / a;
	long long q = n / b;
	long long pq = n / lcm(a, b);
	
	long long ans = n - p - q + pq;
	cout << ans << endl;
}