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;
class Program
{
	static void Main(string[] args)
	{
		/*// 整数の入力
		int a = int.Parse(Console.ReadLine());*/
		// スペース区切りの整数の入力
		string[] input = Console.ReadLine().Split(' ');
		int k = int.Parse(input[0]);
		int s = int.Parse(input[1]);
		// 文字列の入力
		//string s = Console.ReadLine();
		//出力
        int count = 0;
        for(int x=0; x<=k; x++){
            for(int y=0; y<=k; y++){
                for(int z=0; z<=k; z++){
                    if(x+y+z == s) count++;
                }
            }
        }
		Console.WriteLine(count);
	}
}