#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;

ll n,a,b;
ll gcd(ll a, ll b){
    if(b == 0) return a;
    return gcd(b, a % b);
}
int main(){
    cin >> n >> a >> b;
    ll lcm = (a * b) / gcd(a, b);
    cout << n - (n /a) - (n / b) + (n / lcm);
}