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: Wrong Answer)

var

  S : ansistring;
  
begin

  readln(S);

    while pos('dreameraser', S) <> 0 do
      delete(S, pos('dreameraser', S), 11);
      
    while pos('dreamerase', S) <> 0 do
      delete(S, pos('dreamerase', S), 10);
      
    while pos('dreamererase', S) <> 0 do
      delete(S, pos('dreamererase', S), 12);
      
    while pos('dreamereraser', S) <> 0 do
      delete(S, pos('dreamereraser', S), 13);
    
    while pos('dreamer', S) <> 0 do
      delete(S, pos('dreamer', S), 7);
      
    while pos('dream', S) <> 0 do
      delete(S, pos('dream', S), 5);
      
    while pos('eraser', S) <> 0 do
      delete(S, pos('eraser', S), 6);
    
    while pos('erase', S) <> 0 do
      delete(S, pos('erase', S), 5);
    
    if length(S) = 0 then
      writeln('YES')
    else
      writeln('NO');

end.