#include<bits/extc++.h>
using namespace std;
using ll=long long;
int main(){
	ll T,A,B;
	cin>>T>>A>>B;
	T--;
	__int128_t N=(__int128_t)A*B/gcd(A,B);
	ll mns;
	if(N>T)mns=0;
	else mns=T/lcm(A,B);
	cout<<T/A+T/B-mns+1<<endl;
}