D

#include<iostream>
using namespace std;
int main(){
int n,x,y,ans;
cin >> n >> x >> y;
if(y%x!=0){
ans= n-(y/x+1);
}else{
ans= n-y/x;
}
if(ans>0){
cout << ans;
}else{
cout << 0;
}
return 0;
}