#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)
{
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));
}
}
for (auto g : govno)
{
Suffix.insert(g);
}
auto r = Suffix.upper_bound({sum + K , 0});
if (r != Suffix.end() && (r->first) == sum + K)
{
ans = min(ans, (r->second) - depth);
}
}
return Suffix;
};
dfs(0, -1, 0, 1);
return (ans == LLONG_MAX ? -1 : ans);
}
