#include <bits/stdc++.h>
#include "race.h"
//
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ll mask){return __builtin_ctzll(mask);}
int logOf(ll mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T& container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
const int N = 2e5 + 69;
const int INF = 1e9 + 69;
int n, k, ans;
vector<pair<int, int>> graph[N];
map<ll, int> dp[N];
void dfs(int u, int p, int h, ll l){
dp[u][l] = h;
for(auto v: graph[u]) if (v.first != p){
dfs(v.first, u, h + 1, l + v.second);
if (dp[u].size() < dp[v.first].size()) swap(dp[u], dp[v.first]);
for(auto i: dp[v.first]){
ll _l = k - (i.first - l) + l;
if (dp[u].count(_l)) minimize(ans, i.second + dp[u][_l] - 2 * h);
}
for(auto i: dp[v.first]) {
if (dp[u].count(i.first)) minimize(dp[u][i.first], i.second);
else dp[u][i.first] = i.second;
}
}
}
int best_path(int _n, int _k, int H[][2], int L[]){
n = _n; k = _k, ans = INF;
for(int i= 0; i<=n; ++i) {
graph[i].clear();
dp[i].clear();
}
for(int i = 0; i<n-1; ++i){
int u = H[i][0], v = H[i][1], w = L[i];
graph[u].push_back({v, w});
graph[v].push_back({u, w});
}
dfs(0, 0, 0, 0);
if (ans == INF) return -1;
return ans;
}
// int main(void){
// ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
// return 0;
// }
