{
TASK:necklace
LANG:Pascal
}

program neclace;
  var i,b,n:integer;
      A:array[1..60] of longint;

  begin
  readln(n);
  A[1]:=0;
  A[2]:=1;
  A[3]:=1;
  for i:=4 to n do
                begin
        if i mod  2 = 0 then
      A[i]:=(A[i-1]*2) + 1    ;
    if i mod 2 <>0 then
      A[i]:=(A[i-1]*2) - 1;
                     end;
  writeln(A[n]);

  end.