#include "race.h"
#include <bits/stdc++.h>
using namespace std;
#define ff first
#define ss second
int n, k, mn;
vector< pair<int, int> > g[200005];
set<pair<long long, int> > st;
long long depth[200005];
int edges[200005];
void dfs(int v, int par){
st.insert(make_pair(depth[v], v));
if(depth[v] >= k){
auto it = st.lower_bound(make_pair(depth[v] - k, -100));
while(it != st.end()){
if(it->ff != depth[v] - k) break;
// cout << "ans ";
// cout << v << " " << it->ss << '\n';
mn = min(mn, abs(edges[v] - edges[it->ss]));
it++;
}
}
// cout << v << " = ";
// cout << depth[v] << "\n";
for(auto [to, w] : g[v]){
if(to == par) continue;
depth[to] = depth[v] + w;
edges[to] = edges[v] + 1;
dfs(to, v);
}
st.erase(make_pair(depth[v], v));
}
int best_path(int N, int K, int H[][2], int L[]){
n = N, k = K, mn = N+1;
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, 0);
if(mn == n+1) mn = -1;
return mn;
}
//main(){
// int N, K; cin >> N >> K;
// int H[N-1][2], L[N-1];
// for(int i = 0; i < N-1; i++){
// cin >> H[i][0] >> H[i][1];
// }
// for(int i = 0;i < N-1; i++) cin >> L[i];
// cout << best_path(N, K, H, L);
//}
