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 PHP7 (7.0.15) (judge verdict: Wrong Answer)

<?php
$stdin = trim(fgets(STDIN));
$ar = explode(" ",$stdin);
$K = $ar[0];
$S = $ar[1];
$sum=0;
$iandj=false;
//全部同じなら1追加，全部違ったら3追加，のこりは2
for($i=0;$i<=$K;$i++){
        for($j=0;$j<=$i;$j++){
                if($i==$j)$iandj=true;
                else $iandj=false;
                for($k=0;$k<=$j;$k++){
                        if($i+$j+$k == $S){
                                $jandk=$j==$k;
                                if(($iandj && $jandk) or !($iandj or $jandk or $k==$i))
                                        $sum+=1;
                                else    $sum+=3;
                        }
                }
        }
}
print ($sum);