#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using Graph = vector<vector<int>>;
long long GCD(long long a,long long b) {
  if(a%b == 0) return b;
  return GCD(b,a%b);
}
int main() {
  long long N; cin >> N;
  long long x = N - 4;
  if(x == 0) {
    cout << 8 << endl;
    return 0;
  }
  if(x < 0) {
    cout << N << endl;
    return 0;
  }
  cout << x * 5ll + 8ll << endl;
}