#include<fstream>
using namespace std;
long p,i,n,k;
int main()
{ifstream f("fact.in");
f>>p;
f.close();
while(k<p)
{ k++;
  n+=5;
  i=n/5;
  while((i%5==0)&&(i>0))
	  {k++; i=i/5;}}
ofstream g("fact.out");
if(p==0)
	g<<1;
else
	g<<n;
g.close();
return 0;}