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 Fortran (gfortran v4.8.4) (judge verdict: Accepted)

program	main
  implicit none
  integer k,s,i,j
  integer,allocatable::a(:,:)
  read*,k,s
  allocate(a(k+1,k+1))
  forall(i=0:k,j=0:k)a(i+1,j+1)=s-i-j


  print*,count(a.ge.0.and.a.le.k)
!  print*,a.ge.0                                                                

     !forall(j=0:k)a(i+1,j+1)=i+j                                               
end program main