#include <iostream>
#include <fstream>
using namespace std;
ifstream fin ("fact.in");
ofstream fout ("fact.out");
 int main ()
 {
 int p , c ;
    long long stanga , dreapta , m , x ;
    stanga=1 ;dreapta=1000000000 ;
    fin >> p ;
    while(stanga<=dreapta)
        {
            m=(stanga+dreapta)/2 ;
            x=m ;
            c=0 ;
            while(m!=0)
                {
                    c=c+m/5 ;
                    m=m/5;
                }
            if(c==p)
                {
                    if(x-x%5==0) fout << "1" ;
                        else fout << x-x%5 ;
                    dreapta=-1 ;
                }
            else if (c>p) dreapta=(stanga+dreapta)/2-1 ;
                else stanga=(stanga+dreapta)/2+1 ;
        }
    if(dreapta!=-1) 
		fout << "-1" ;
    return 0;
 }