#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-1)/a+(t-1)/b-(t-1)/lcm(a,b)+1<<'\n';
	return 0;
}