#include <bits/stdc++.h>

using namespace std;
using ll = long long;
ll gcd(ll a, ll b){
	return a%b ? gcd(b,a%b) : b;
}
int main(){
    
    ll t, a, b;
    cin >> t >> a >> b;
    --t;
    ll ans = 0;
    ans += t/a+1;
    ans += t/b+1;
    ans -= t/(a/gcd(a, b)*b);
    cout << ans-1 << endl;
    
    
    return 0;
}