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 Haskell (judge verdict: Accepted)

module Main where
import Debug.Trace
import Data.List
import Data.Array
import Data.Maybe
import Data.Ord
import Control.Monad

solve :: [[Int]] -> [Int]
solve [] = []
solve ([n, t]:ds) = length (traverse [] 3 [1..n]) : solve ds where
    traverse tc 0 xs = if sum tc == t then [tc] else []
    traverse tc _ [] = []
    traverse tc r (x:xs) = traverse (x:tc) (r-1) xs ++ traverse tc r xs 

readLine:: IO [Int]
readLine = fmap (map read . words) getLine

readUntil :: ([Int] -> Bool) -> IO [[Int]]
readUntil eof = iter where
    iter = readLine >>=
            (\a -> if eof a then return [] else fmap (a:) iter)
            
eof :: [Int] -> Bool
eof (n:x:xs) = all (== 0) [n, x] 

main :: IO() 
main = do
    l   <- readUntil eof
    mapM_ print (solve l)