#include <bits/stdc++.h>
#define pt(sth) cout << sth << "\n"
#define itr(x,c) for(auto x=c.begin();x!=c.end();x++)
#define ritr(x,c) for(auto x=c.rbegin();x!=c.rend();x++)
#define all(a) (a.begin()),(a.end())
#define rall(a) (a.rbegin()),(a.rend())
using namespace std;
#include <atcoder/all>
using namespace atcoder;
typedef long long ll;
typedef pair<ll, ll> pll;
template<class T>bool chmax(T &a, const T &b) {if(a<b) {a=b; return 1;} return 0;}
template<class T>bool chmin(T &a, const T &b) {if(b<a) {a=b; return 1;} return 0;}
static const ll INF=1e18;
static const ll MAX=101010;
static const ll MOD=1e9+7;
static const double PI=acos(-1);
static const double eps=1e-10;
//static const ll MOD=998244353;
//for(i=0;i<N;i++)cin>>a[i];

typedef vector<ll> v1d;
typedef vector<v1d> v2d;
typedef vector<v2d> v3d;
typedef vector<v3d> v4d;



int main(void) {
  ll i,j,k;
  /*
  ll N;cin>>N;
  v1d a(N);
  for(i=0;i<N;i++)cin>>a[i];
  */
  
  ll N;cin>>N;
  ll ans=(N>=3?(N-3)*5+3:N);
  
  pt(ans);
  
  
  
}