The package for this problem was not updated by the problem writer or Codeforces administration after we've upgraded the judging servers. To adjust the time limit constraint, a solution execution time will be multiplied by 2. For example, if your solution works for 400 ms on judging servers, then the value 800 ms will be displayed and used to determine the verdict.

Croc Champ 2013 - Round 2 |
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Finished |

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data structures

divide and conquer

trees

*2700

No tag edit access

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E. Close Vertices

time limit per test

5 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputYou've got a weighted tree, consisting of *n* vertices. Each edge has a non-negative weight. The length of the path between any two vertices of the tree is the number of edges in the path. The weight of the path is the total weight of all edges it contains.

Two vertices are close if there exists a path of length at most *l* between them and a path of weight at most *w* between them. Count the number of pairs of vertices *v*, *u* (*v* < *u*), such that vertices *v* and *u* are close.

Input

The first line contains three integers *n*, *l* and *w* (1 ≤ *n* ≤ 10^{5}, 1 ≤ *l* ≤ *n*, 0 ≤ *w* ≤ 10^{9}). The next *n* - 1 lines contain the descriptions of the tree edges. The *i*-th line contains two integers *p*_{i}, *w*_{i} (1 ≤ *p*_{i} < (*i* + 1), 0 ≤ *w*_{i} ≤ 10^{4}), that mean that the *i*-th edge connects vertex (*i* + 1) and *p*_{i} and has weight *w*_{i}.

Consider the tree vertices indexed from 1 to *n* in some way.

Output

Print a single integer — the number of close pairs.

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64d specifier.

Examples

Input

4 4 6

1 3

1 4

1 3

Output

4

Input

6 2 17

1 3

2 5

2 13

1 6

5 9

Output

9

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