```c
//#include <iostream>
//#include <algorithm>
//#include <string>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main()
{
double x,z;
cin>>x>>z;
double c;
cin>>c;
ll nums;
nums=ceil((x-2*z)/c);
cout<<nums<<endl;
return 0;
}
```
by adminh @ 2024-05-11 20:02:45