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

class Scanner
{
    private $arr = [];
    private $count = 0;
    private $pointer = 0;

    public function next()
    {
        if ($this->pointer >= $this->count) {
            $str = trim(fgets(STDIN));
            $this->arr = explode(" ", $str);
            $this->count = count($this->arr);
            $this->pointer = 0;
        }
        $result = $this->arr[$this->pointer];
        $this->pointer++;
        return $result;
    }

    public function hasNext()
    {
        return $this->pointer < $this->count;
    }

    public function nextInt()
    {
        return (int)$this->next();
    }

    public function nextDouble()
    {
        return (double)$this->next();
    }
}

class out
{
    public static function printIn($str = "")
    {
        echo $str . PHP_EOL;
    }
}

$sc = new Scanner;

$K = $sc->nextInt();
$S = $sc->nextInt();
$count = 0;

for ($x = 0; $x < $K; $x++) {
    for ($y = 0; $y < $K; $y++) {
        for ($z = 0; $z < $K; $z++) {
            $sum = $x + $y + $z;
            if ($sum === $S) {
                $count++;
            }
        }
    }
}
echo $count;