#include<bits/stdc++.h>
#define int long long
#define double long double
using namespace std;
signed main(){
    int n,a,b;cin>>n>>a>>b;
    int cnt_a,cnt_b,cnt_c;
    cnt_a=n/a;
    cnt_b=n/b;
    cnt_c=n/(lcm(a,b));
    cout<<n-(cnt_a+cnt_b-cnt_c)<<endl;
}