Problem:
Score : 200 points

Problem Statement

You are given two integers K and S.

Three variable X, Y and Z takes integer values satisfying 0≤X,Y,Z≤K.

How many different assignments of values to X, Y and Z are there such that X + Y + Z = S?

Constraints

2≤K≤2500

0≤S≤3K

K and S are integers.

Input

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

K S

Output

Print the number of the triples of X, Y and Z that satisfy the condition.

Sample Input 1

2 2

Sample Output 1

6

There are six triples of X, Y and Z that satisfy the condition:

X = 0, Y = 0, Z = 2

X = 0, Y = 2, Z = 0

X = 2, Y = 0, Z = 0

X = 0, Y = 1, Z = 1

X = 1, Y = 0, Z = 1

X = 1, Y = 1, Z = 0

Sample Input 2

5 15

Sample Output 2

1

The maximum value of X + Y + Z is 15, achieved by one triple of X, Y and Z.

Solution in Pascal (FPC 2.6.2) (judge verdict: Time Limit Exceeded)

program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils;
var
  k,s,x,y,z,sum:Integer;
begin
  try
    { TODO -oUser -cConsole Main : ここにコードを記述してください }
    Read(k);
    Readln(s);

    sum:=0;

    for z := 0 to k do begin
      for y := 0 to k do begin
        for x := z to k do begin
          if x+y+z=s then begin
            if x=z then
              Inc(sum)
            else
              sum:=sum+2;
            Break;
          end;
        end;
      end;
    end;

    Writeln(sum);
    Readln;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
end.