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


int main() {
    long long T, A, B;
    cin >> T >> A >> B;
    long long ans = (T - 1) / A + (T - 1) / B - ((T - 1) / A) / (B / gcd(A, B)) + 1;
    cout << ans << endl;

    return 0;
}