#include <iostream>
using namespace std;
int main(){
    int a = 0;
    int x = 0;
    int c = 0;
    int sum = 0;
    cin >> a >> x >> c;
    if(x%c==0)
	{
		sum=c/x;
	}
    else 
    {
        sum=c/x+1;
    }
    cout<<a-sum;
	return 0;
}