#include<bits/stdc++.h>
using namespace std;

int max_choco(int N) {
    int choco = N;
    int empty_pac = N;


    while (empty_pac>= 2) {

        int new_choco = empty_pac / 2;
        choco += new_choco;


        empty_pac = empty_pac % 2 + new_choco;
    }

    return choco;
}

int main() {
    int N;
    cin >> N;

    cout << max_choco(N) << endl;

}