#include <fstream>
#include <algorithm>

using namespace std;

const int L = 30;

ifstream in("fact.in");
ofstream out("fact.out");

int zero(int n)
{
    int nrz = 0;
    while(n >= 5)
    {
        nrz += (n /= 5);
    }
    return nrz;
}

int main()
{
    int n, p, pas, r;
    in >> p;
    pas = 1 << L;
    r = 0;
    while(pas != 0)
    {
        if(zero(r+pas)<p)
        {
            r+=pas;
        }
        pas /= 2;
    }
    r++;
    out << r;

    return 0;
}