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time limit per test: 0.25 sec.

memory limit per test: 65536 KB

memory limit per test: 65536 KB

input: standard

output: standard

output: standard

Inspired by a "Little Bishops" problem, Petya now wants to solve problem for rooks.

A rook is a piece used in the game of chess which is played on a board of square grids. A rook can only move horizontally and vertically from its current position and two rooks attack each other if one is on the path of the other.

Given two numbers n and k, your job is to determine the number of ways one can put k rooks on an n × n chessboard so that no two of them are in attacking positions.

A rook is a piece used in the game of chess which is played on a board of square grids. A rook can only move horizontally and vertically from its current position and two rooks attack each other if one is on the path of the other.

Given two numbers n and k, your job is to determine the number of ways one can put k rooks on an n × n chessboard so that no two of them are in attacking positions.

The input file contains two integers n (1 ≤ n ≤ 10) and k (0 ≤ k ≤ n

Print a line containing the total number of ways one can put the given number of rooks on a chessboard of the given size so that no two of them are in attacking positions.

Input

4 4

Output

24

Author: | Andrew Stankevich |

Resource: | Little Chess Pieces Series, SPb IFMO 2003-2004 Authumn Training Sessions |

Date: | 2003-10-01 |

Codeforces (c) Copyright 2010-2020 Mike Mirzayanov

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