# 1278. Binomial Showdown

In how many ways can you choose k elements out of n elements, not taking order into account?

Write a program to compute this number.

### 输入格式

The input will contain one or more test cases.

Each test case consists of one line containing two integers n (n>=1) and k (0<=k<=n).

Input is terminated by two zeroes for n and k.

### 输出格式

For each test case, print one line containing the required number. This number will always fit into an integer, i.e. it will be less than 2^31.

Warning: Don’t underestimate the problem. The result will fit into an integer - but if all intermediate results arising during the computation will also fit into an integer depends on your algorithm. The test cases will go to the limit.

### 样例

Input
4 2
10 5
49 6
0 0

Output
6
252
13983816


21 人解决，35 人已尝试。

27 份提交通过，共有 148 份提交。

5.7 EMB 奖励。