#include <fstream>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int main()
{
    int p,n=0,exp=0,aux;
    in>>p;
    if(p==0)
    {
        out<<1;
        return 0;
    }
    while(p>exp)
    {
        n+=5;
        aux=n;
        while(aux%5==0)
        {
            aux/=5;
            exp++;
        }
    }
    if(p==exp)
    {
        out<<n;
        return 0;
    }
    if(p<exp)
    {
        out<<-1;
        return 0;
    }
}