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 Julia (0.5.0) (judge verdict: Accepted)

parseInt(x) = parse(Int,x)

function main()
	k,s = map(parseInt, split(readline()))
	if s <= k
		println(div((s+1)*(s+2),2))
	elseif s <= 2*k
		println((k+1)*(k+1)-div((s-k)*(s-k+1),2)-div((2*k-s)*(2*k-s+1),2))
	else
		println(div((3*k-s+1)*(3*k-s+2),2))
	end
end

main()