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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n, a, b;
    cin >> n >> a >> b;
    ll c = lcm(a, b);
    cout << n - n / a - n / b + n / c << '\n';
}