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

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

int nr_zero(int n){
    int nr = 0;
    while ( n > 0){
        nr += n/5;
        n /= 5;
    }
    return nr;
}

const int L = 28;
int p, n, cif, k;


int main()
{
    in >> p;
    int r = 0, pas = 1 << 28;
    while (pas != 0)
    {
        if(nr_zero(r + pas) < p)
        {
            r += pas;
        }
        pas /= 2;
    }
    r++;
    if ( nr_zero(r) != p)
    {
        //out << - 1;
        r = -1;
    }
    out << r;
    return 0;
}