#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int nrzero(int n)
{
    int nr = 0;
    while (n >= 5)
    {
        nr += n / 5;
        n /= 5;
    }
    return nr;
}

int main()
{
    int n,p;
    in>>p;
    int r = 0;
    int pas = 1<<30;
    while (pas != 0)
    {
        if (nrzero(r + pas) < p)
            r += pas;
        pas /= 2;
    }
    if (nrzero(1 + r) == p)
        cout<<1 + r;
    else
        cout<<-1;
    return 0;
}