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Problems > Closed Walks on Decagon

Closed Walks on Decagon

Difficulty: 1800 4000 ms 128 MB

graphs matrix-exponentiation

Count the closed walks of length N from vertex 1 in Decagon, modulo 109+7.

Input: one integer N.

Output: the number of closed walks mod 109+7.

Constraints:

  • 0 ≤ N ≤ 1018

Sample Tests

Input 1
2
Output 1
2
Input 2
0
Output 2
1

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