#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
main()
{
    ifstream f1("fact.in");
    ofstream f2("fact.out");
    int n=0, p, pow2=0, pow5=0;
    f1>>p;
    while (min(pow2,pow5) < p)
    {
        n++;
        while (n%2 == 0){
            n = n / 2;
            pow2++;
        }
        while (n % 5 == 0){
            n = n / 5;
            pow5++;
        }
    }
    f2<<n;
}