[PKU] P1306: Combinations

Description

Computing
the exact number of ways that N things can be taken M at a time can be
a great challenge when N and/or M become very large. Challenges are the
stuff of contests. Therefore, you are to make just such a computation
given the following:
GIVEN: 5 <= N <= 100; 5 <= M <= 100; M <= N

Compute the EXACT value of: C = N! / (N-M)!M!

You may assume that the final value of C will fit in a 32-bit
Pascal LongInt or a C long. For the record, the exact value of 100! is:

93,326,215,443,944,152,681,699,238,856,266,700,490,715,968,264,381,621,
468,592,963,895,217,599,993,229,915,608,941,463,976,156,518,286,253,
697,920,827,223,758,251,185,210,916,864,000,000,000,000,000,000,000,000

Input

The
input to this program will be one or more lines each containing zero or
more leading spaces, a value for N, one or more spaces, and a value for
M. The last line of the input file will contain a dummy N, M pair with
both values equal to zero. Your program should terminate when this line
is read.

Output

The output from this program should be in the form:

N things taken M at a time is C exactly.

Sample Input

Sample Output

Source

Solution:

[#M_ more.. | less.. |
_M#]

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