#include <iostream>
#include <fstream>
#include <cmath>
using namespace std;
int main()
{
    ifstream fin("fact.in");
    ofstream fout("fact.out");
    int n, ct=0, p=0;
    fin>>n;
    while(ct!=n)
    {
        p+=5;
        double logaritm = (log(p))/(log(5));
        if (logaritm==floor(logaritm)) ct += logaritm;
        else ct++;
    }
    fout<<p;
}