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

using ll = long long;

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

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

int main() {
    ll t, a, b;
    cin >> t >> a >> b;
    t--;
    ll ans = t / a + t / b - t / lcm(a, b) + 1;
    cout << ans << endl;
}