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 Pascal (FPC 3.0.4) (judge verdict: Time Limit Exceeded)

var
  cnt,k,s,x,y,z:longint;
begin
  readln(k,s);
  if (s=3*k) then begin
    writeln('1');
    exit;
  end;
  cnt:=0;
  if (s<k) then begin
      for x:=0 to s do
        for y:=0 to s do
          for z:=0 to s do
            if (x+y+z=s) then
              inc(cnt);
  end
  else begin
    for x:=0 to k do
        for y:=0 to k do
          for z:=0 to k do
            if (x+y+z=s) then
              inc(cnt);
  end;
  writeln(cnt);
end.