program Project4;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils;
var x, i: Integer;
var b: Boolean;
begin
  try
  x:=0;
    i := 0;
    b := true;
    while True do
    begin
      if i <> 0 then
      x := i;
      ReadLn(i);
      if i = 0 then  break;
      if (x <> 0) and (i >= x) then b := false;
    end;
    if b then WriteLn('Yes')
    else WriteLn('No');
    ReadLn;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.