#include "bits/stdc++.h"

using namespace std;

void solve()
{
    long t, a, b;
    cin >> t >> a >> b;
    long g = __gcd(a, b), c = a * b / g;
    cout << (t + a - 1) / a + (t + b - 1) / b - (t + c - 1) / c << endl;
}

int main()
{
    solve();
    return 0;
}