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
  $input = explode(" ", fgets(STDIN));
  $K = intval($input[0]);
  $S = intval($input[1]);
  
  $count = 0;
  for ($x = 0; $x <= $K; $x++) {
    for ($y = 0; $y <= $K; $y++) {
      // K以内でx + y = z
      $z = $S - ($x + $y);
      // S - x + y を保存してて、K以内だったらまたif分にいく
      if ($z <= $K) {
        if ($x + $y + $z == $S) {
          $count++;
        }
      }
    }
  }
  echo $count;