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

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

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(20);
 
    ll t,a,b;
    cin>>t>>a>>b;
    t--;
    ll g = gcd(a,b);
    ll l = a*b/g;
    ll ans = t/a + t/b -t/l;
    ans++;
    cout << ans << endl; 
    


}