program cch(input,output);
var
 f:array[0..1000] of string;
 k,i:integer;

procedure swap(var s1,s2:string);
var
 s3:string;
begin
 s3:=s1;
 s1:=s2;
 s2:=s3;
end;

function add(s1,s2:string):string;
var
 i,l,l1,l2:integer;
 a,b,c:array[1..300] of integer;
 s3:string;
begin
 l1:=length(s1); l2:=length(s2);
 for i:=1 to l1 do a[i]:=ord(s1[l1-i+1])-48;
 for i:=1 to l2 do b[i]:=ord(s2[l2-i+1])-48;
 if l1>l2 then
  begin
   l:=l1;
   for i:=l2+1 to l do b[i]:=0;
  end
 else
  begin
   l:=l2;
   for i:=l1+1 to l do a[i]:=0;
  end;
 for i:=1 to l+1 do c[i]:=0;
 for i:=1 to l do
  begin
   c[i]:=c[i]+a[i]+b[i];
   c[i+1]:=c[i] div 10;
   c[i]:=c[i] mod 10;
  end;
 if c[l+1]<>0 then inc(l);
 s3:='';
 for i:=1 to l do s3:=s3+chr(c[l-i+1]+48);
 add:=s3;
end;

function mul(s1,s2:string):string;
var
 a,b,c:array[1..300] of integer;
 i,j,l,l1,l2:integer;
 s3:string;
begin
 l1:=length(s1); l2:=length(s2);
 for i:=1 to l1 do a[i]:=ord(s1[l1-i+1])-48;
 for i:=1 to l2 do b[i]:=ord(s2[l2-i+1])-48;
 l:=l1+l2+1;
 for i:=1 to l do c[i]:=0;
 for i:=1 to l1 do
  for j:=1 to l2 do
   c[i+j]:=c[i+j]+a[i]*b[j];
 for i:=2 to l1+l2 do
  begin
   c[i+1]:=c[i+1]+c[i] div 10;
   c[i]:=c[i] mod 10;
  end;
 while (l>2)and(c[l]=0) do dec(l);
 s3:='';
 for i:=2 to l do s3:=s3+chr(c[l-i+2]+48);
 mul:=s3;
end;

function sub(s1,s2:string):string;
var
 l1,l2,l,i:integer;
 a,b,c:array[1..300] of integer;
 s3:string;
begin
  l1:=length(s1); l2:=length(s2);
  if l1<l2 then begin write('-'); swap(s1,s2); end;
  if l1=l2 then
    if s1<s2 then begin write('-'); swap(s1,s2); end;
  l1:=length(s1); l2:=length(s2);
  for i:=1 to l1 do a[i]:=ord(s1[l1-i+1])-48;
  for i:=1 to l2 do b[i]:=ord(s2[l2-i+1])-48;
  if l1>l2 then
     begin
      l:=l1;
      for i:=l2+1 to l do b[i]:=0;
     end
   else
     begin
      l:=l2;
      for i:=l1+1 to l do a[i]:=0;
     end;
  for i:=1 to l do c[i]:=0;
  for i:=1 to l do
   begin
    if a[i]<b[i] then
      begin
        inc(a[i],10);
        dec(a[i+1]);
      end;
    c[i]:=a[i]-b[i];
   end;
  while (l>1)and(c[l]=0) do dec(l);
  s3:='';
  for i:=1 to l do s3:=s3+chr(c[l-i+1]+48);
  sub:=s3;
 end;

begin
 assign(input,'zbfa.in');
 assign(output,'zbfa.out');
 reset(input);
 rewrite(output);
 readln(k);
 f[0]:='1'; f[1]:='3';
 for i:=2 to k do
  f[i]:=add(mul('2',sub(f[i-1],f[i-2])),mul('3',f[i-2]));
 write(f[k]);
 close(input);
 close(output);
end.