#include <stdio.h>
long long i, t, p;
int main(void)
{
freopen("fact.in", "r", stdin);
freopen("fact.out", "w", stdout);
scanf("%lld", &p);
for (i=1;;i++)
	{
   p--;
	if (i%5==0)
   	{
      t=i;
      while (t%5==0)
         {
      	p--;
         t/=5;
         }
      }
   if (p<=0)
   	break;
   }
printf("%lld", 5*i);
fcloseall();
return 0;
}