Problem:
How many ways?

Write a program which identifies the number of combinations of three integers which satisfy the following conditions:

You should select three distinct integers from 1 to n.

A total sum of the three integers is x.

For example, there are two combinations for n = 5 and x = 9.

1 + 3 + 5 = 9

2 + 3 + 4 = 9

Input

The input consists of multiple datasets. For each dataset, two integers n and x are given in a line.

The input ends with two zeros for n and x respectively. Your program should not process for these terminal symbols.

Constraints

3 ≤ n ≤ 100

0 ≤ x ≤ 300

Output

For each dataset, print the number of combinations in a line.

Sample Input

5 9
0 0

Sample Output

2

Note

      解説

Solution in C# (judge verdict: Accepted)

using System;
using System.Linq;

class Problem {
    public static void Combination(int n, int x, int s, int t, int l, ref int c) {
        for (var i = s + 1; i <= n; i++) {
            if (l != 3) Combination(n, x, i, t + i, l + 1, ref c);
            else c += t + i == x ? 1 : 0;
        }
    }
    
    public static void Main() {
        var str = "";
        while ((str = Console.ReadLine()) != "0 0") {
            var data = str.Split().Select(int.Parse).ToArray();
            var count = 0;
            Combination(data[0], data[1], 0, 0, 1, ref count);
            Console.WriteLine(count);
        }
    }
}