#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, srt, end) for (long long i = (srt); i < (long long)(end); i++)

void solve() {
    ll n;
    cin >> n;
    if(n <= 3) {
        cout << n << endl;
    } else {
        cout << 3 + (n - 3) * 5 << endl;
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
    return 0;
}