using namespace std;
#include<iostream>
#include<fstream>

int main()
{
    ifstream fin("fact.in");
    ofstream fout("fact.out");

    unsigned long p;
    unsigned long n = 0;
    unsigned long nrzerouri = 0;

    fin >> p;

    if (p == 0) {
        n = 1;
    } else {
        while (nrzerouri < p) {
            n = n + 5;
            int cn = n;
            while (cn % 5 == 0) {
                cn = cn / 5;
                nrzerouri++;
            }
        }
    }

    fout << n;

    fin.close();
    fout.close();

    return 0;
}