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 C# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApp23
{
    class Program
    {

        static void Main(string[] args)
        {
            var line = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            var k = line[0];
            var s = line[1];

            var counter = 0;
            for (int x = 0; x <= k; x++)
            {
                for (int y = 0; y <= k; y++)
                {
                    for (int z = 0; z <= k; z++)
                    {
                        var sum = z + x + y;
                        if (sum == s)
                        {
                            counter++;
                        }
                    }
                }
            }

            Console.WriteLine(counter);
        }


    }

}