#include <bits/stdc++.h>
#include "race.h"
using ll =long long;
//#define int ll
ll LINF=1000000000000000000;
int INF=1000000000;
#define pi pair<int,int>
#define pl pair<ll,ll>
#define endl '\n'
#define vi vector<int>
#define vii vector<vector<int>>
#define vl vector<ll>
#define vll vector<vector<ll>>
//#define int ll
using namespace std;
vector<vector<pi>>g;
int k;
int minimum=1e9;
void dfs(int node, int parent,int nodes, int dist){
if(dist==k)minimum=min(minimum,nodes);
if(dist>=k)return;
if(nodes>=minimum)return;
for(auto p:g[node]){
if(p.first==parent)continue;
dfs(p.first,node,nodes+1,dist+p.second);
}
};
int best_path(int N, int K, int H[][2], int L[])
{
g.resize(N);
k=K;
for(int i=0;i<N-1;i++){
g[H[i][0]].push_back(make_pair(H[i][1],L[i]));
g[H[i][1]].push_back(make_pair(H[i][0],L[i]));
}
for(int i=0;i<N;i++){
dfs(i,-1,0,0);
}
if(minimum==1e9)return -1;
return minimum;
}
