// basic file operations
#include <iostream>
#include <fstream>
#include <math.h>
using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");
long n, m, P;

int suma(int j, int k)
{
    long s = 0;
    for (int i = 1; i <= k; i++)
        s += floor(j / pow(5, i));
    return s;
}

long factorial(long P)
{
    int i;
    long a, b, j;

    if (P == 0)
    {
        return 1;
    }

    m = 1;
    for (i = 1; m <= P; i++)
        m += pow(5, i);
    if (P == m - 1)
        return -1;
    else
        m -= pow(5, --i);
    a = ceil(P * pow(5, i) / m);
    b = floor((P + i) * pow(5, i) / m);
    for (j = a; j < b; j++)
        if (suma(j, i) == P)
            return j;
    return -1;
}

int main()
{
    fin >> P;

    fout << factorial(P);

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

    return 0;
}