#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("factorial.in");
ofstream fout("factorial.out");

int main()
{
    int nr;
    fin>>nr;
    if(nr==0)
    {
        fout<<1;
        return 0;
    }
    int n=1;
    int nr_fact = 0;
    while(nr_fact<nr)
    {
        if(n%5==0)
        {
            int cn=n;
            while(cn!=0 && cn%5==0)
            {
                nr_fact++;
                cn/=5;
            }

        }
        n++;
    }
    fout<<n-1;
    return 0;

}