#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define all(x) (x).begin(), (x).end()
#define ll long long
#define ld long double
#define INF 1000000000000000000
typedef pair<ll, ll> pll;

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

long long LCM(long long a, long long b) { return a / GCD(a, b) * b; }

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll T, A, B;
    cin >> T >> A >> B;
    T--;
    ll gcd = LCM(A, B);
    cout << (T / A + 1) + (T / B + 1) - (T / gcd + 1) << endl;
    return 0;
}