#include <iostream>
using namespace std;

long long gcd(long long a, long long b) {
	if (b == 0) return a;
	return gcd(b, a % b);
}

long long N, A, B;

int main() {
	cin >> N >> A >> B;
	long long L1 = (N - 1) / A;
	long long L2 = (N - 1) / B;
	long long M = gcd(A, B);
	long long L3 = L1 / (B / M);
	cout << L1 + L2 - L3 + 1 << endl;
	return 0;
}