How many ways?
  Write a program that calculates the number of combinations of three different integers that satisfy the following conditions:
You must choose three different integers from 1 to n.
The sum of the three integers is x.
  For example, if n = 5 and x = 9, there are two combinations:
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 on one line.
  The input is terminated by two zeros (n and x). Do not process the program for these end symbols.
Constraints
3 ≤ n ≤ 100
0 ≤ x ≤ 300
Output
  For each dataset, output the number of combinations on one line.
Sample Input
5 9
0 0
Sample Output
2
Note
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