#include<iostream>
#include<string>
#include<queue>
#include<algorithm>
#include<map>
#include<set>
#include<vector>
#include<math.h>

using namespace std;

#define INF 1000000007
#define LINF (1LL << 62)

typedef long long i64;
typedef pair<i64,i64> P;


i64 gcd(i64 x, i64 y){
	if(y == 0) return x;
	return gcd(y, x%y);
}

i64 n,a,b;


i64 lcm(i64 x, i64 y){
	if(x/gcd(x,y) > n/y) return LINF;
	return x / gcd(x,y) * y;
}

int main(){
	cin >> n >> a >> b;
	n--;
	cout << n/a + n/b - n/lcm(a,b) + 1 << endl;
	
	return 0;
}