#include <iostream>
#include <algorithm>
using namespace std;
typedef long long ll;

ll gcd(ll a,ll b);

int main(void){
    ll t,a,b,ans;
    cin >> t >> a >> b;
    ans=(t-1)/a+(t-1)/b-(t-1)/(a*b)*gcd(a,b);
    cout << ans << endl;
    return 0;
}

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