#include <iostream>

using namespace std;

int main()
{
    int n, a, b;
    cin >> n >> a >> b;
    int kolicnik_a = 0;
    kolicnik_a = n/a;
    int kolicnik_b = 0;
    kolicnik_b = n/b;
    cout << kolicnik_b - kolicnik_a << endl;
     return 0;
}