#include <fstream>

using namespace std;
ifstream cin("fact.in");
ofstream cout("fact.out");
int P;
int nrzero(int nr);
int main()
{
    int pas = 1 << 30, i = 0;
    cin >> P;
    while(pas)
    {
        int nrz = nrzero(i + pas);
        if(nrz <= P - 1) i += pas;
        pas /= 2;
    }
    if(nrzero(i + 1) == P)
    cout << i + 1;
    else cout << -1;
    return 0;
}
int nrzero(int n)
{
        int nrz = 0;
        while(n > 1)
        {
            nrz += n / 5;
            n /= 5;
        }
        return nrz;

}