#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
#define rep(i,n) for(int i=0;i<n;i++)

signed main() {
  double x,y,r;
  cin>>x>>y>>r;
  for(int i=1;i<=500;i++){
    if((pow(x*x+y*y,0.5)+r)*2 < pow(((double)i)*((double)i)*2,0.5)){
      cout<<i<<endl;
      return 0;
    }
  }
  return 0;
}