#include "race.h"
#include<bits/stdc++.h>
using namespace std;
int n, k;
vector<vector<pair<int, int>>> g;
vector<map<int, int>> d;
int mn = 2e9;
bool have_ans = false;
void dfs(int v, int prev) {
for(auto [u, w]: g[v]) {
if(prev == u) continue;
dfs(u, v);
d[v][w] = 1;
for(int i = w+1; i <= k; i++) {
if(!d[u].count(i-w)) continue;
if(d[v].count(i)) d[v][i] = min(d[v][i], d[u][i-w]+1);
else d[v][i] = d[u][i-w]+1;
}
}
if(d[v].count(k)) {
mn = min(mn, d[v][k]);
have_ans = true;
}
}
int best_path(int N, int K, int H[][2], int L[]) {
n = N; k = K;
g.assign(n, vector<pair<int, int>>());
d.assign(n, map<int, int>());
for(int i = 0; i < n-1; i++) {
g[H[i][0]].push_back({H[i][1], L[i]});
g[H[i][1]].push_back({H[i][0], L[i]});
}
dfs(0, -1);
if(have_ans) return mn;
return -1;
}
