#include <iostream>
#include <fstream>
using namespace std;

int main()
{ifstream fin("fact.in");
ofstream fout("fact.out");

int p,i,k=0;
fin>>p;
i=0;
while(k!=p)
{ i=i+5;
 if(i%5==0) {if(i%25==0) {if(i%125==0) {if(i%625==0) {if(i%3125==0) k=k+5;
                                                      else k=k+4;

                                                     }
                                         else k=k+3;


                                       }
                            else k=k+2;
                         }
             else k=k+1;
            }

}
fout<<i;

    return 0;
}