#include <bits/stdc++.h>
#define rep(i,n) for(int i=(0);i<(n);i++)

using namespace std;

typedef long long ll;

ll gcd(ll a, ll b){
	if(b == 0) return a;
	return gcd(b, a % b);
}

ll lcm(ll a, ll b){
	return a / gcd(a, b) * b;
}

int main()
{
	cin.tie(0);
	ios::sync_with_stdio(false);

	ll t, a, b;
	cin >> t >> a >> b;
	t--;

	cout << t / a + t / b - t / lcm(a, b) + 1 << endl;

}