#include "race.h"
#include <vector>
#include <queue>
#include <iostream>
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
using namespace std;
const int N = 200001;
int att[N];
int biju[N];
int len[N];
vector<vector<pair<int,int>>> g(N);
void DFS(int v1){
for(auto p : g[v1]){
if(!biju[p.second]){
biju[p.second] = 1;
att[p.second] = att[v1] + p.first;
len[p.second] = len[v1] + 1;
DFS(p.second);
}
}
}
int best_path(int N, int K, int H[][2], int L[])
{
//cout << "test1";
for(int i = 0;i < N - 1;i++)
{
int u = H[i][0], v = H[i][1], w = L[i];
g[u].push_back({v, w});
g[v].push_back({u, w});
}
//cout << "test";
int res = -1;
for(int i = 0; i < N; i++){
//fill(att,att+N, 0);
fill(biju,biju+N, 0);
att[i] = len[i] = 0;
biju[i] = 1;
//cout << "test2";
DFS(i);
//cout << "test3";
for(int j = 0;j < N;j++){
//cout << att[j] << ' ' << len[j] << '\n';
if(att[j] == K && (res == -1 || len[j] < res))
res = len[j];
}
}
//cout << res/2;
return res;
}
