#include <iostream>
#include <fstream>
using namespace std;
int p;
long long i=5, c;
int main()
{
    ifstream fin("fact.in");
    ofstream fout("fact.out");
    fin>>p;
    if (!p)
        fout<<1;
    else
    {
        while (p)
        {
            c=i;
            while (c%5==0)
            {
                p--;
                c/=5;

            }
            i+=5;
        }
        fout<<i-5;
    }

    return 0;
}