#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    fstream file;
    unsigned int p, n, i, n5;
    bool ok;

    file.open("fact.in", ios::in);
    file >> p;
    file.close();

    file.open("fact.out", ios::out);

    if(p == 0) {
        file << 1 << endl;
    } else {
        n5 = p / 5;

        for(i = 1, ok = false; i <= n5; ++i) {
            if(!((p - n5 + i) % 5)) {
                ok = true;
                break;
            }
        }
        if(ok) {
            n = (p - n5 + 1) * 5;
        } else {
            n = (p - n5) * 5;
        }

        if(!((p - n5 + 1) % 5)) {
            file << -1 << endl;
        } else {
            file << n << endl;
        }
    }

    file.close();

    return 0;
}