#include <iostream>
#include <fstream>
using namespace std;
int main()
{long p,aux,nr;
ifstream f("fact.in");
ofstream g("fact.out");
f>>p;
nr=5;
if(p<100000000)
g<<"-1";
else
if (p==0) g<<"1";
else
{ while (p>0)
{
    aux=nr;
    while(aux%5==0)
    {
        aux=aux/5;
        p=p-1;
    }
    nr=nr+5;
}
g<<nr-5;
}
f.close();
g.close();
return 0;
}