#include <fstream>

using namespace std;

int main()
{
   ifstream  fin("fact.in");
   ofstream fout("fact.out");
   int P, N=1,N1,zerouri=0;
   fin >> P;
   if(P>=0){
   while(zerouri!=P)
   {   ++N;
       N1=N;
       while(N1%5==0 && zerouri!=P)
      {
    ++zerouri;
       N1=N1/5;}
   }
   if(N1%5==0)
    fout <<"-1";
   else
   fout << N;
   }
   else
    fout << "-1";
    return 0;
}