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

template<typename T>
void fin(T a){
  cout<<a<<endl;
  exit(0);
}

signed main(){
  int x,y,r;cin>>x>>y>>r;
  x=abs(x);y=abs(y);
  for(double i=0;;i+=0.5)if(i*i+i*i>=r*r)fin(x+y+(int)(i*2+0.5));
}