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

#define int long long

signed main(){
    int t, a, b;
    cin >> t >> a >> b;

    t--;
    int l = a / __gcd(a, b) * b;
    int ans = t/a + t/b - t/l + 1;

    cout << ans << endl;

    return 0;
}