#include <bits/stdc++.h>
#include "race.h"
using namespace std;
vector<vector<pair<int, int>>> g;
vector<vector<int>> dp;
int k;
void dfs(int u, int p) {
dp[u][0] = 0;
for (auto [v, w] : g[u]) {
if (v == p) continue;
dfs(v, u);
for (int i = w; i <= k; i++) {
dp[u][i] = min(dp[u][i], dp[v][i - w] + 1);
}
}
}
int best_path(int N, int K, int H[][2], int L[]) {
k = K;
g.resize(N);
dp.resize(N, vector<int>(K + 1, N + 1));
for (int i = 0; i < N - 1; i++) {
int u = H[i][0], v = H[i][1], w = L[i];
g[u].push_back({v, w});
g[v].push_back({u, w});
}
dfs(0, -1);
int res = N + 1;
for (int i = 0; i < N; i++) {
res = min(res, dp[i][k]);
}
return (res == N + 1 ? -1 : res);
}
