#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <climits>

using namespace std;

FILE * f = fopen("factorial.in", "r");
FILE * g = fopen("factorial.out", "w");

int main()
{
    int zerouri = 0, n, p = 25, z = 5, ok = 0;
    fscanf(f, "%i", &n);
    if (n == 0)
    {
        ok = 1;
        fprintf(g, "%i", 1);
    }
    else
    {
        for (int i = 5; i <= 100000000 && ok == 0; i += 5)
        {
            p = 25;
            z = 5;
            zerouri = 0;
            zerouri = i / z;
            while (p <= i)
            {
                zerouri += i / p;
                p *= z;
            }
            if (zerouri == n)
            {
                ok = 1;
                fprintf(g, "%i", i);
            }
        }
    }
    if (ok == 0)
    {
        fprintf(g, "%i", -1);
    }
    return 0;
}