#atcoderABC070D. Transit Tree Path

Transit Tree Path

Problem Statement

You are given a tree with NN vertices.
Here, a tree is a kind of graph, and more specifically, a connected undirected graph with N1N-1 edges, where NN is the number of its vertices.
The ii-th edge (1iN1)(1≤i≤N-1) connects Vertices aia_i and bib_i, and has a length of cic_i.

You are also given QQ queries and an integer KK. In the jj-th query (1jQ)(1≤j≤Q):

  • find the length of the shortest path from Vertex xjx_j and Vertex yjy_j via Vertex KK.

Constraints

  • 3N1053≤N≤10^5
  • 1ai,biN(1iN1)1≤a_i,b_i≤N (1≤i≤N-1)
  • 1ci109(1iN1)1≤c_i≤10^9 (1≤i≤N-1)
  • The given graph is a tree.
  • 1Q1051≤Q≤10^5
  • 1KN1≤K≤N
  • 1xj,yjN(1jQ)1≤x_j,y_j≤N (1≤j≤Q)
  • xjyj(1jQ)x_j≠y_j (1≤j≤Q)
  • xjK,yjK(1jQ)x_j≠K,y_j≠K (1≤j≤Q)

Input

Input is given from Standard Input in the following format:

NN

a1a_1 b1b_1 c1c_1

::

aN1a_{N-1} bN1b_{N-1} cN1c_{N-1}

QQ KK

x1x_1 y1y_1

::

xQx_{Q} yQy_{Q}

Output

Print the responses to the queries in QQ lines.
In the jj-th line j(1jQ)j(1≤j≤Q), print the response to the jj-th query.

Input 1

5
1 2 1
1 3 1
2 4 1
3 5 1
3 1
2 4
2 3
4 5

Output 1

3
2
4

The shortest paths for the three queries are as follows:

  • Query 11: Vertex 22 → Vertex 11 → Vertex 22 → Vertex 44 : Length 1+1+1=31+1+1=3
  • Query 22: Vertex 22 → Vertex 11 → Vertex 33 : Length 1+1=21+1=2
  • Query 33: Vertex 44 → Vertex 22 → Vertex 11 → Vertex 33 → Vertex 55 : Length 1+1+1+1=41+1+1+1=4

Input 2

7
1 2 1
1 3 3
1 4 5
1 5 7
1 6 9
1 7 11
3 2
1 3
4 5
6 7

Output 2

5
14
22

The path for each query must pass Vertex K=2K=2.

Input 3

10
1 2 1000000000
2 3 1000000000
3 4 1000000000
4 5 1000000000
5 6 1000000000
6 7 1000000000
7 8 1000000000
8 9 1000000000
9 10 1000000000
1 1
9 10

Output 3

17000000000