#include <iostream>
using namespace std;
typedef long long ll;
ll n,a,b,c,ans;
ll gcd(ll x,ll y){
    if(y==0)return x;
    return gcd(y,x%y);
}
int main(void){
    cin>>n>>a>>b;
    c=a/gcd(a,b)*b;
    ans+=(n+a-1)/a;
    ans+=(n+b-1)/b;
    ans-=(n+c-1)/c;
    cout<<ans<<endl;
}