Let's consider K-based numbers, containing exactly N digits. We define a number to be valid if its K-based notation doesn't contain two successful zeroes.
Example: 1010230 is a valid 7-digit number 1000198 is not a valid number 0001235 is not a 7-digit number, it is a 4-digit number.
Given two numbers N and K, you are to calculate an amount of valid K based numbers, contaning N digits.
You may assume that 2 <= K <= 10; 2 <= N; 4 <= N+K <= 18.
Input two decimal numbers N and K
Output The result in decimal notation.
Sample Input 2 10
Sample Output 90