#include <iostream>
#include <cmath>
using namespace std;
int main(int argc, char** argv) {
  int x, y, r;
  cin >> x >> y >> r;
  if (x < 0) x = -x;
  if (y < 0) y = -y;
  double tmp;
  int ans;
  if (x == 0 && y == 0) tmp = sqrt(2) * r;
  else tmp = (x + y) * (1 + r / sqrt(x * x + y * y));
  ans = (int)tmp + 1;
  cout << ans << endl;
  return 0;
}