#include <fstream>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int zerouri(int n)
{
    int s=0,putere=5;
    while(putere<=n)
    {
        s=s+n/putere;
        putere=putere*5;
    }
    return s;
}
int main()
{
    int n,st=1,dr=2000000000,p,x,nr,a,m=1;
    in>>p;
    if(p==0) out<<1<<'\n';
    else
    {
        while(st<=dr&&m)
        {
            x=(st+dr)/2;
            a=zerouri(x);
            if(a==p)
            {
                nr=x-x%5;
                m=0;
            }
            else if(a<p) st=x+1;
                 else dr=x-1;
        }
        if(m==0) out<<nr<<'\n';
        else out<<-1<<'\n';
   }
}