#include <bits/stdc++.h>
using namespace std;
typedef long long  ll;
typedef vector<int> VI;
typedef vector<ll> VLL;

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

int main(){
    ll t,a,b,ans = 1;
    cin >> t >> a >> b;

    unsigned long long lcm = a/gcd(a,b)*b;
    --t;
    ans += t/a + t/b - t/lcm;

    cout << ans << endl;
    return 0;
}