#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;
using ll = long long;
int main() {
  ll n;
  cin >> n;
  if(n <= 3) {
    cout << n << endl;
  } else {
    cout << 3 + (n - 3) * 5 << endl;
  }
  return 0;
}