#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
//using mint = modint1000000007;
using mint = modint998244353;
template <typename T> bool chmax(T &u, const T z) { if (u < z) {u = z; return true;} else return false; }
template <typename T> bool chmin(T &u, const T z) { if (u > z) {u = z; return true;} else return false; }
#define ll long long
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
typedef pair<ll, int> P;
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
ll lcm(ll a, ll b){return a * b / gcd(a, b);}

int main(){
  ll n;
  cin>>n;
  if(n<=3){
    cout<<n<<endl;
    return 0;
  }else{  
    ll ans=3+(n-3)*5;
    cout<<ans<<endl;
    return 0;
  }
}