#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
#define endl '\n'
typedef unsigned int uint;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
using namespace std;
// #include "race.h"
int best_path(int N, int K, int H[][2], int L[])
{
vector<vector<pair<ll,ll>>>rebr(N+1);
for(int i = 0;i < N-1;i++){
rebr[H[i][0]].push_back({H[i][1],L[i]});
rebr[H[i][1]].push_back({H[i][0],L[i]});
}
ll ans = LLONG_MAX;
function< set< pair<ll,ll> >(ll ,ll,ll , ll)> dfs;
dfs = [&](ll x , ll p , ll sum , ll depth){
set< pair<ll,ll> > Suffix;
Suffix.insert({sum , depth});
for(auto g: rebr[x]){
if(g.first==p)continue;
set< pair<ll,ll> > govno = dfs(g.first , x , sum+g.second ,depth+1);
if(Suffix.size() < govno.size()){
swap(govno, Suffix);
}
for(auto g: govno){
Suffix.insert(g);
}
}
for(auto g: Suffix){
if(g.first == sum+K){
ans = min(g.second-depth ,ans);
continue;
}
auto r = Suffix.upper_bound({sum+sum+K - g.first , 0});
if(r != Suffix.end() && (r->first) == sum+sum+K - g.first){
ans = min(ans , g.second+r->second - (depth*2) );
}
}
return Suffix;
};
dfs(1 , 0 , 0 , 0);
return (ans == LLONG_MAX ? -1 : ans);
}
