#include <iostream>
#include <fstream>
#include <math.h>
using namespace std;
int numara_zerouri(int nr)
{
    int nr_zerouri=0;
    while(nr>=5)
    {
        nr_zerouri+=nr/5;
        nr=nr/5;
    }
    return nr_zerouri;
}
int main()
{
   ifstream fin("fact.in");
   ofstream fout("fact.out");
   int P,i,nr,rez=0;
   fin>>P;
   nr=int(pow(2,30));
   while(nr!=0)
   {
       if(numara_zerouri(rez+nr)<P)
         rez=rez+nr;
       nr=nr/2;
   }
   if(numara_zerouri(rez+1)==P)
       fout<<rez+1;
   else
       fout<<-1;
   fin.close();
   fout.close();
   return 0;
}