#include "race.h"
#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MAXN = 2e5+5;
const int inf = 2e9;
int n, r;
vector<array<int,2>> g[MAXN];
int ans;
array<int,2> d[MAXN];
map<int,int> sg[MAXN];
void dfs(int x, int p){
sg[x][d[x][1]] = d[x][0];
for(auto [k,w] : g[x]){
if(k==p) continue;
d[k][0] = d[x][0]+1;
d[k][1] = d[x][1]+w;
dfs(k,x);
if(sg[k].size() > sg[x].size()){
swap(sg[x], sg[k]);
}
for(auto p : sg[k]){
int t = r+2*d[x][1]-p.first;
if(sg[x].find(t)!=sg[x].end()) ans = min(ans, p.second+sg[x][t]-2*d[x][0]);
}
for(auto p : sg[k]){
if(sg[x].find(p.first)!=sg[x].end()) sg[x][p.first] = min(sg[x][p.first], p.second);
else sg[x][p.first] = p.second;
}
sg[k].clear();
}
}
int32_t best_path(int32_t N, int32_t K, int32_t H[][2], int32_t L[]){
n = N; r = K;
ans = inf;
for(int i = 0; i < n; ++i){
g[i].clear();
sg[i].clear();
}
for(int i = 0; i < n-1; ++i){
int x = H[i][0], y = H[i][1], w = L[i];
g[x].push_back({y,(long long)w});
g[y].push_back({x,(long long)w});
}
dfs(0,0);
return (ans==inf ? -1 : ans);
}
