#include <iostream>
#include <fstream>
#include <math.h>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
int p ,n ,m5 ,aux;
int main()
{
    f>>p;
    n=0;
    m5=0;
    if(p==0)
        g<<1;
    else
    {
    while(m5<p)
    {
        n=n+5;
        aux=n;
        while(aux%5==0)
        {
            aux=aux/5;
            m5++;
        }

    }
    g<<n;
    }
    return 0;
}