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