#include <fstream>

using namespace std;

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

int nz(int n) {
    int f = 5, r = 0;
    while (n>=f) {
        r+=n/f;
        f *= 5;
    }
    return r;
}

int P, N;

int main() {
    cin >> P;
    if (P) {
        N = 5 * P;
        while (nz(N)>P)
            N -= 5;

        if (nz(N)<P) {
            cout << -1;
        } else {
            cout << N;
        }
    } else {
        cout << 1;
    }

    cin.close();
    cout.close();
    return 0;
}