#include <iostream>
#include <fstream>

using namespace std;

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

int countZeroes(int n)
{
    int counter = 0;

    for (int i = 5; n / i >= 1; i *= 5)
        counter += n / i;

    return counter;
}

int main()
{
    bool found = false;

    int p;
    in >> p;

    int n;

    if(p == 0){
        out << 1 << '\n';
    } else {
        if(p < 0){
            out << -1 << '\n';
        } else {
            for(int i = p; i <= p * 5; ++i){
                if(p == countZeroes(i)){
                    n = i;
                    found = true;
                    break;
                }
            }

            if(found == true){
                out << n << '\n';
            } else {
                out << -1 << '\n';
            }
        }
    }

}