//
//  main.cpp
//  factorial
//
//  Created by Andru Zuniga on 14.12.2013.
//  Copyright (c) 2013 Andru Zuniga. All rights reserved.
//

#include <iostream>
#include <fstream>

using namespace std;

int main(int argc, const char * argv[])
{

    int n, limita, baza = 0, vector[13] = {1, 6, 31, 156, 781, 3906, 19531, 97656, 488281, 2441406, 12207031, 61035156, 1000000001};
    ifstream fin("fact.in");
    fin >> n;
    fin.close();
    if(n == 0)
        baza = 1;
    while (n > 0) {
        limita = 0;
        while (vector[limita] <= n) {
            limita++;
        }
        limita--;
        baza += (n / vector[limita]) * (vector[limita] - vector[limita - 1]) * 5;
        n -= (n / vector[limita]) * vector[limita];
    }
    ofstream fout("fact.out");
    fout << baza;
    fout.close();
    return 0;
}