#include <bits/stdc++.h>
using namespace std;
int main() {
  double a, b, c, d, dis, r;
  int ans = 0;
  cin >> a >> b >> c >> d >> r;
  dis = sqrt(((a - c) * (a - c)) + ((b - d) * (b - d)));
  while (dis > 0.00) {
    dis = -r;
    ans++;
  }
  cout << ans;
  return 0;
}
