#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<queue>
#include<map>
#include<math.h>
#include<iomanip>
#include<set>
#include<numeric>
#include<cstring>
#include<cstdio>
#include<functional>
#include<bitset>
#include<limits.h>
#include<cassert>
#include<iterator>
#include<complex>
#include<stack>
using namespace std;
#define lint long long int
/*
vector<char>al(26);
al = {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
vector<char>AL(26);
AL = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
*/

lint euc(lint a, lint b) {
	if (a < b) return euc(b, a);
	lint r;
	while ((r = a % b)) {
		a = b;
		b = r;
	}
	return b;
}

int main() {
	lint T, A, B;
	cin >> T >> A >> B;
	if (T == 1) {
		cout << 0 << endl;
	}
	else {
		cout << (T - 1) / A + (T - 1) / B - (T - 1) / (A * B / euc(A, B)) + 1 << endl;
	}
}