/* -*- coding: utf-8 -*-
 *
 * 1992.cc:  No.1992 Tendon Walk - yukicoder
 */

#include<cstdio>
#include<algorithm>
 
using namespace std;

/* constant */

const int K = 7;
const int ds[K] = { 2, 2, -1, -1, 2, -1, -1 };

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int x;
  scanf("%d", &x);

  int p = 0, l = 0;
  for (int i = 0;; i++) {
    int di = ds[i % K];
    p += di;
    l += abs(di);
    if (p == x) break;
  }

  printf("%d\n", l);
  return 0;
}