Problem:
Score : 200 points

Problem Statement

Let w be a string consisting of lowercase letters.
We will call w beautiful if the following condition is satisfied:

Each lowercase letter of the English alphabet occurs even number of times in w.

You are given the string w. Determine if w is beautiful.

Constraints

1 \leq |w| \leq 100

w consists of lowercase letters (a-z).

Input

The input is given from Standard Input in the following format:

w

Output

Print Yes if w is beautiful. Print No otherwise.

Sample Input 1

abaccaba

Sample Output 1

Yes

a occurs four times, b occurs twice, c occurs twice and the other letters occur zero times.

Sample Input 2

hthth

Sample Output 2

No

Solution in Pascal (FPC 2.6.2) (judge verdict: Wrong Answer)

program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils,Classes;
var
  i,j,min:Integer;
  w:string;
  sw:Char;
  beau:Boolean;
begin
  try
    { TODO -oUser -cConsole Main : ここにコードを記述してください }
    Readln(w);

    for i := 1 to Length(w) do begin
      min := i;
      for j := i+1 to Length(w) do begin
        if w[j] < w[min] then
        min := j;
      end;
      sw:=w[i];
      w[i]:=w[min];
      w[min]:=sw;
    end;

    beau:=True;
    if Length(w) mod 2 = 1 then
      beau:=false
    else begin
      i:=1;
      while i<Length(w) do
        if w[i]=w[i+1] then
          i:=i+2
        else begin
          beau:=false;
          Break;
        end;
    end;

    if beau then   
      Writeln('YES')
    else
      Writeln('NO');
    Readln;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.