Problem:
Score : 200 points

Problem Statement

There are N balls placed in a row.
AtCoDeer the deer is painting each of these in one of the K colors of his paint cans.
For aesthetic reasons, any two adjacent balls must be painted in different colors.

Find the number of the possible ways to paint the balls.

Constraints

1≦N≦1000

2≦K≦1000

The correct answer is at most 2^{31}-1.

Input

The input is given from Standard Input in the following format:

N K

Output

Print the number of the possible ways to paint the balls.

Sample Input 1

2 2

Sample Output 1

2

We will denote the colors by 0 and 1. There are two possible ways: we can either paint the left ball in color 0 and the right ball in color 1, or paint the left in color 1 and the right in color 0.

Sample Input 2

1 10

Sample Output 2

10

Since there is only one ball, we can use any of the ten colors to paint it. Thus, the answer is ten.

Solution in Scala (2.11.7) (judge verdict: Wrong Answer)

import java.util.Scanner

object Main {
  def main(args: Array[String]): Unit = {
    val sc = new Scanner(System.in)
    val n, k = BigInt(sc.nextBigInteger())
    println(k * pow(n, k - 1))
  }

  def pow(n: BigInt, k: BigInt): BigInt = {
    if (k == 0) {
      1
    } else if (k == 1) {
      n
    } else if (k % 2 == 0) {
      pow(n * n, k / 2)
    } else {
      n * pow(n, k - 1)
    }
  }
}