#include<bits/stdc++.h>
using namespace std;
using ll =long long;

#include<atcoder/dsu>
using namespace atcoder;


void solve(){
	ll N,A,B;
	cin>>N>>A>>B;
	ll g=gcd(A,B);
	cout<<N-(N/A)-(N/B)+(N/(A*B/g))<<endl;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);


	int T=1;
	// cin>>T;
	while(T--)solve();
	
}