#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG_
#include <compe/debug.hpp>
#else
#define dump(...)
#endif

#define FastIO cin.tie(nullptr), ios_base::sync_with_stdio(false);
#define rep(i, n) for (int i = 0; (int)i < n; ++i)
#define output(msg) cout << (msg) << '\n'
#define die(msg)         \
  do {                   \
    cout << msg << endl; \
    exit(0);             \
  } while (0)

template <typename T> bool chmax(T& a, const T& b) {
  return ((a < b) ? (a = b, true) : (false));
}
template <typename T> bool chmin(T& a, const T& b) {
  return ((a > b) ? (a = b, true) : false);
}

using llint = long long int;

int main() {
  FastIO;

  int x;
  cin >> x;

  int pos{0}, dist{0};
  while (true) {
    // a a
    pos += 2;
    dist += 2;
    if (pos == x) break;

    pos += 2;
    dist += 2;
    if (pos == x) break;

    // b b
    pos -= 1;
    dist += 1;
    if (pos == x) break;

    pos -= 1;
    dist += 1;
    if (pos == x) break;

    // a
    pos += 2;
    dist += 2;
    if (pos == x) break;

    // b b
    pos -= 1;
    dist += 1;
    if (pos == x) break;

    pos -= 1;
    dist += 1;
    if (pos == x) break;
  }
  output(dist);
}