#include <iostream>
#include <fstream>

using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int n;
long long v[1000000];
int main()
{
    in >> n;
    if (!n)
    {
        out << 1;
        return 0;
    }
    int c = n * 5 - (((n * 5) / 25 - 1) * 5);
    if (c % 25 == 0) {
        out << -1;
        return 0;
    }
    for (int i = 1; i <= n; i++)
        v[i] = i * 5;
    int l, m, r;
    l = 1;
    r = n;
    while (true) {
        m = (l + r) / 2;
        if ((v[m] / 5 + v[m] / 25) == n)
            break;
        else if ((v[m] / 5 + v[m] / 25) < n)
            l = m + 1;
        else r = m - 1;
    }
    out << v[m];
    return 0;
}