Hiring process8 levels
  1. 1 IQ Test
  2. 2 Additional Online Test (If Required)
  3. 3 Office Interview with Hiring Manager
  4. 4 Unpaid Test Task (Motivation Check)
  5. 5 Paid Test Task and Follow-Up Interview
  6. 6 Iterative Paid Test Tasks
  7. 7 Office Verification
  8. 8 Final Interview with the Founder

Problems > Painting the Fence

Painting the Fence

Difficulty: 1400 4000 ms 128 MB

math combinatorics

Paint a row of N planks with K colours so no two adjacent planks share a colour. Count the ways, modulo 109+7.

Input: one line with two integers N and K.

Output: the number of valid colourings mod 109+7.

Constraints:

  • 1 ≤ N ≤ 1018
  • 1 ≤ K ≤ 109

Sample Tests

Input 1
3 2
Output 1
2
Input 2
1 5
Output 2
5

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