#include <iostream>
#include <fstream>
using namespace std;
ifstream f("factorial.in");
ofstream g("factorial.out");
int main()
{
    int i,t,s,p;
    f>>p;
    if (p==0)
        g<<1;
    else
    {
        s=0;
        i=0;
        while(s<p)
        {
            i=i+5;
            t=i;
            while(t%5==0)
            {
                t=t/5;
                s++;
            }
        }
    g<<i;
    }
    return 0;
}