#abc220e. [abc220_e]Distance on Large Perfect Binary Tree
[abc220_e]Distance on Large Perfect Binary Tree
Problem Statement
We have a tree with vertices.
The vertices are numbered through . For each , the following edges exist:
- an undirected edge connecting Vertex and Vertex ,
- an undirected edge connecting Vertex and Vertex .
There is no other edge.
Let the distance between two vertices be the number of edges in the simple path connecting those two vertices.
Find the number, modulo , of pairs of vertices such that the distance between them is .
Constraints
- All values in input are integers.
Input
Input is given from Standard Input in the following format:
Output
Print the answer.
Sample Input 1
3 2
Sample Output 1
14
The following figure describes the given tree.
There are pairs of vertices such that the distance between them is : $(1,4),(1,5),(1,6),(1,7),(2,3),(3,2),(4,1),(4,5),(5,1),(5,4),(6,1),(6,7),(7,1),(7,6)$.
Sample Input 2
14142 17320
Sample Output 2
11284501