#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define MAX 200003
#define MOD 998244353
#define INF 1000000000

int main(){
  int x,y,r;
  cin>>x>>y>>r;
  x=abs(x);
  y=abs(y);
  //d>x+y+r*sqrt(2);
  //(d-x-y)^2>2*r^2
  for(int i=x+y;;i++){
    if((i-x-y)*(i-x-y)>2*r*r){
      cout<<i<<endl;
      return 0;
    }
  }
}