#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){
auto it = st.lower_bound(make_pair(depth[v] - k, -1));
while(it != st.end()){
if(it->ff != depth[v] - k) break;
mn = min(mn, abs(edges[v] - edges[it->ss]));
}
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[]){
st.insert({0, 0});
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(1, 1);
if(mn == n+1) mn = -1;
return mn;
}
//main(){
//
//}
