/*
TASK: necklace
LANG: C++
*/
#include<iostream.h>
#include<math.h>
	unsigned long long a[101],b[70];
	unsigned long long br,br1,br2,br0,n,x,y,p,q,x1;
int main()
{
cin>>n;
if(n<=25)
{
 x=2<<n-1;
 x1=2<<n-2;
 for(br=x1; br<=x; br++)
 {
  br1=0;
  y=br;
  p=0;
  q=0;
  do
  {
   br1++;
   b[br1]=y%2;
   y/=2;
  }
  while(y!=0);
  if(b[n]==1)
  {
   for(br0=1; br0<=n; br0++)
   {
	if(b[br0]==1 && br0%2==0) q++;
	if(b[br0]==1 && br0%2==1) p++;
   }
   if((abs(p-q))%3==0) br2++;
  }
 }
 cout<<br2<<endl;
}
else
{
 a[1]=0;
 a[2]=1;
 a[3]=1;
 a[4]=3;
 a[5]=5;
 a[6]=11;
 a[7]=21;
 for(br=8; br<=n; br++)
 {
  for(br1=1; br1<=br; br1++)
   a[br]+=a[br1];
 }
 cout<<a[n]<<endl;
}
return 0;
}
