#include <fstream>

using namespace std;
long long p,n,ok=1,k=0,a;
int main()
{
    ifstream fin("fact.in");
    ofstream fout("fact.out");
    fin>>p;
    if(p==0)
    fout<<1;
    else
    {

        while(ok)
        {
            k=k+5;
            a=k;
            while(a%5==0&&p>0)
            {
                a=a/5;
                p--;

            }
            if(p<=0)
                ok=0;
        }

        if(p==0)
            fout<<k;
        else fout<<-1;
    }
    return 0;
}