#include <bits/stdc++.h>

#define rep(i,n) for(int i=0;i<(n);i++)

using namespace std;
using lint=long long;

int main(){
	lint t,a,b; cin>>t>>a>>b;
	cout<<t/a+t/b-t/lcm(a,b)<<'\n';
	return 0;
}