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 Ruby (judge verdict: Accepted)

#!/usr/bin/env ruby

def comb(n, x)
    if x > n*3-3 or x < 6 then
        return []
	end

    c = []
    for i in 1..n-2 do
        if i > x/3 then
            break
		end
        for j in i+1..n-1 do
            if j > (x-i)/2 then
                break
			end
            rem = x-(i+j)
            if rem > j and rem <= n then
                c += [[i, j, rem]]
			end
		end
	end

    return c

end

if __FILE__ == $0 then
	loop do
		n, x = gets.split.map(&:to_i)

		if [n, x] == [0, 0] then
			break
		end
		puts comb(n, x).size
	end
end