#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, x, I = 0;
  cin >> n;
  for (int i = 1; i <= 1000; i++) {
    if ((i * i) >= n) {
      x = (i * i);
      I = i;
      break;
    }
  }
  int res = x - n;
  int ans1 = -1, y = 0, z = 0;
  if (res == 0) {
    ans1 = I * 4;
  }
  if ((res / I) >= 1) {
    y = (I * (I - (res / I)));
    z = res % I;
    ans1 = (I * 2) + ((I - (res / I)) * 2);
  }
  if ((res / I) == 0) {
    ans1 = I * 4;
  }
  cout << ans1 << endl;
  return 0;
}
