# 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

## Output

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

## Sample Input

5 9
0 0

## Sample Output

2

## Note

解説