#include "race.h"
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define endl '\n'
#define INF 1e9+7
#define all(x) x.begin(),x.end()
using namespace std;
using namespace __gnu_pbds;
using ll=long long;
using pii=pair<int,int>;
using ppi=pair<int,pii>;
using oset=tree<int,null_type,less<int>,rb_tree_tag,tree_order_statistics_node_update>;
template<typename T>
void _print(vector<T> x) {cerr<<"{"; for(auto e:x) cerr<<e<<","; cerr<<"}";}
void _print(pii x) {cerr<<"{"<<x.first<<","<<x.second<<"}";}
template<typename T>
void _print(T x) {cerr<<x;}
void dbg() {cerr<<endl;}
template<typename Head,typename... Tail>
void dbg(Head H,Tail... T) {
_print(H);
if(sizeof...(T)) cerr<<",";
else cerr<<"\"]";
dbg(T...);
}
#define debug(...) cerr<<"["<<#__VA_ARGS__<<"]:[\"",dbg(__VA_ARGS__)
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int mxn=2e5+10;
int n,k;
vector<pii> adj[mxn];
int solve(int u,int p,int sum) {
if(!sum) return 0;
if(sum<0) return -1;
int res=INF;
for(auto vw:adj[u]) {
int v=vw.first, w=vw.second;
if(v==p) continue;
int temp=solve(v,u,sum-w);
if(temp!=-1) res=min(res,1+temp);
}
if(res==INF) return -1;
return res;
}
int best_path(int N, int K, int H[][2], int L[])
{
n=N,k=K;
for(int i=0;i<n-1;i++) {
int u=H[i][0],v=H[i][1],w=L[i];
adj[u].push_back({v,w});
adj[v].push_back({u,w});
}
int ans=INF;
for(int i=0;i<n;i++) {
int temp=solve(i,i,k);
if(temp!=-1) ans=min(ans,temp);
}
if(ans==INF) return -1;
return ans;
}
