#include<iostream>
#include<vector>
#include<math.h>
#include<iomanip>
#include<numeric>
using namespace std;

int main() {
	long long N,A,B;
	cin>>N>>A>>B;
	long long a = N/A;
	long long b = N/B;
	long long ab = N/(lcm(A,B));
	cout << N - a - b + ab << endl;
}