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 Perl (5.26.1) (judge verdict: Accepted)

use strict;

my @a = split(' ',<>);
my $k = @a[0];
my $s = @a[1];
my $ans = 0;

for(my $i=0; $i<=$k; $i++) {
  for (my $j=0; $j<=$k; $j++) {
    if ($i + $j > $s){
      next;
    }

    if ($s - ($i + $j) <= $k) {
      $ans += 1;
    }
  }
}


print($ans);