#include <bits/stdc++.h>

using namespace std;

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

int main()
{
    int nr = 0,p,i = 0,x,add;
    in >> p;
    if (p == 0)
        out << 1;
    else
    {
        while (nr < p)
        {
            i += 5;
            x = i;
            add = 0;
            while (x % 5 == 0)
            {
                x /= 5;
                add++;
            }
            nr += add;
        }
        if (nr == p)
            out << i;
        else
            out << -1;
    }
    return 0;
}