var a:array[1..1001] of byte;
    f,g:text;
    n,i,j,nr,x:integer;
    ok:boolean;
begin
assign(f,'nunta.in');reset(f);
assign(g,'nunta.out');rewrite(g);
readln(f,n);
nr:=0;
for i:=1 to 1 shl n do begin
    x:=i;
    for j:=1 to n do begin
        a[j]:=x mod 2;
        x:=x div 2;
    end;
    ok:=true;j:=1;
    while j<=n do
        if (a[j]=0) and (a[j+1]=0) and (j<>n) then j:=j+2 else
           if ((a[j]=0) and (a[j+1]=1)) or ((a[j]=0) and (j=n)) then begin ok:=false;
                                             break;
           end else inc(j);
    if ok=true then inc(nr);
end;
writeln(g,nr);
close(g);
end.