#include "race.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
unordered_map<ll, int> solve(int N, ll K, vector<vector<pair<int, int>>>& es,
int& curmin, int last, int cur) {
// cout << "solve " << cur << "\n";
unordered_map<ll, int> ans;
ans.insert({0, 0});
for (auto [next, len] : es[cur]) {
if (next == last) continue;
unordered_map<ll, int> a = solve(N, K, es, curmin, cur, next);
for (auto [k, v] : a) {
if (k > K) continue;
ll search = K - (k + (ll)len);
auto it = ans.find(search);
if (it != ans.end()) {
curmin = min(curmin, it->second + v + 1);
}
}
for (auto [k, v] : a) {
if (k > K) continue;
ans.insert({k + (ll)len, v + 1});
}
}
return ans;
}
int best_path(int N, int K, int H[][2], int L[]) {
// cout << "testcase\n";
vector<vector<pair<int, int>>> es(N);
for (int i = 0; i < N - 1; i++) {
es[H[i][0]].push_back({H[i][1], L[i]});
es[H[i][1]].push_back({H[i][0], L[i]});
}
int curmin = N;
auto ans = solve(N, K, es, curmin, -1, 0);
if (curmin == N) {
return -1;
} else {
return curmin;
}
}
