#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 = 1e9;
void dfs(int v, int prev) {
d[v][0] = 0;
for(auto [u, w]: g[v]) {
if(prev == u) continue;
dfs(u, v);
for(auto [key, val]: d[u]) {
if(key+w > k) continue;
if(d[v].count(key+w)) {
d[v][key+w] = min(d[v][key+w], val+1);
} else {
d[v][key+w] = val+1;
}
}
}
if(d[v].count(k)) {
mn = min(mn, d[v][k]);
}
}
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(mn < 1e9) return mn;
return -1;
}
