#include<bits/stdc++.h>
using namespace std;

int main(){
	cin.tie(0),ios::sync_with_stdio(false);
	int x,y,r; cin>>x>>y>>r;
	long double mx=sqrtl(x*x+y*y)+r;
	int ans=1;
	while(ans*sqrtl(2)/2<mx)++ans;
	cout<<ans<<"\n"s;
}