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

int main()
{
    long long x;
    cin >> x;
    long long m = x % 11LL;
    long long q = x / 11LL;
    long long ans = 0LL;

    if (1 < m)
        ans++;
    if (7 <= m)
        ans++;
    ans += 2 * q;
    if (m == 1)
        ans++;
    cout << ans << endl;
    return 0;
}
#include <bits/stdc++.h>
#define rep(i, n) for (ll i = 0; i < (ll)(n); ++i)
#define rep2(i, s, n) for (ll i = s; i < (ll)(n); i++)
#define repr(i, n) for (ll i = n; i >= 0; i--)
#define pb push_back
#define COUT(x) cout << (x) << endl
#define COUTF(x) cout << setprecision(15) << (x) << endl
#define ENDL cout << endl
#define DF(x) x.erase(x.begin())  // 先頭文字削除
#define ALL(x) x.begin(), x.end()
#define SORT(x) sort(ALL(x))
#define REVERSE(x) reverse(ALL(x))
#define ANS cout << ans << endl
#define RETURN(x)    \
  cout << x << endl; \
  return 0
#define init() \
  cin.tie(0);  \
  ios::sync_with_stdio(false)
#define debug(x) cerr << "[debug] " << #x << ": " << x << endl;
#define debugV(v)                       \
  cerr << "[debugV] " << #v << ":";     \
  rep(i, v.size()) cerr << " " << v[i]; \
  cerr << endl;
using namespace std;
using ll = long long;
using ld = long double;
using vll = vector<ll>;
using P = pair<ll, ll>;
constexpr ll INF = 0x3f3f3f3f3f3f3f3f;
constexpr ld PI = 3.141592653589793238462643383279;
ll get_digit(ll x) {
  return to_string(x).size();
}

ll gcd(ll x, ll y) {
  return y ? gcd(y, x % y) : x;
}

ll lcm(ll a, ll b) {
  return a / gcd(a, b) * b;
}

vector<P> factorize(ll n) {
  vector<P> result;
  for (ll i = 2; i * i <= n; ++i) {
    if (n % i == 0) {
      result.pb({i, 0});
      while (n % i == 0) {
        n /= i;
        result.back().second++;
      }
    }
  }
  if (n != 1) {
    result.pb({n, 1});
  }
  return result;
}

vll divisor(ll n) {
  vll ret;
  for (ll i = 1; i * i <= n; i++) {
    if (n % i == 0) {
      ret.push_back(i);
      if (i * i != n) ret.push_back(n / i);
    }
  }
  SORT(ret);
  return (ret);
}

template <class T>
inline bool chmin(T& a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T& a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

signed main() {
  init();
  ll N;
  cin >> N;

  ll ans = N / 11;
  ans *= 2;
  ll amari = N % 11;
  if (amari == 0) {
    RETURN(ans);
  }
  if (amari <= 6) {
    ans++;
  } else if (amari <= 11) {
    ans += 2;
  }
  ANS;
  return 0;
}