#include <fstream>
#include <iostream>
std::ifstream fin("fact.in");
std::ofstream fout("fact.out");



int main()
{
    int p;

   fin >> p;

   if(!p) fout << 1;

   size_t i, k;
   for(i = 5; p > 0; i += 5){
         k = i;
         while(!(k%5)) k /= 5, p--;
   }


   if(p < 0) fout << - 1;
    else fout << i - 5;
}