#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#define ll unsigned long long
using namespace std;
const int N=1e5+10;
ll ans,n,a,b,c,d,e;
int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin>>n>>a>>b;
	c=(n/a)*(n/a+1)/2*a,d=(n/b)*(n/b+1)/2*b,e=(n/(a*b))*(n/(a*b)+1)/2*a*b,n=n*(n+1)/2;
	ans=n-c-d+e;
	if(a==b) ans=n-c;
	cout<<ans<<"\n";
	return 0;
}