#include "race.h"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mp make_pair
#define f first
#define s second
const ll inf = 1e18;
vector<vector<pair<ll,ll>>> edges;
vector<bool> centroids;
vector<ll> sizes;
ll n,k;
ll get_size(ll node, ll parent = -1) {
ll res = 1;
for(auto i: edges[node]) {
if(centroids[i.f] || i.f==parent)continue;
res+=get_size(i.f,node);
}
return sizes[node]=res;
}
ll get_centroid(ll node,ll _n,ll parent = -1) {
for(auto i: edges[node]) {
if(centroids[i.f] || i.f == parent)continue;
if(sizes[i.f]*2>_n)
return get_centroid(i.f,_n,node);
}
return node;
}
vector<unordered_map<ll,ll>>dp;
void dfs(ll node,ll val,ll times,ll parent = -1) {
if(dp.back().find(val)==dp.back().end())
dp.back()[val] = times;
else
dp.back()[val] = min(dp.back()[val],times);
for(auto i: edges[node]) {
if(i.f==parent || centroids[i.f]) continue;
dfs(i.f,val+i.s,times+1,node);
}
}
ll solve(ll node,int _n) {
//find centroid;
dp.clear();
get_size(node);
ll centroid = get_centroid(node,_n);
centroids[centroid] = true;
for(auto i: edges[centroid]) {
if(centroids[i.f])continue;
dp.emplace_back();
dfs(i.f,i.s,1);
}
ll ans = inf;
for(int i = 0; i<dp.size(); i++) {
if(dp[i].find(k)!=dp[i].end())
ans = min(ans,dp[i][k]);
for(int j = i+1; j<dp.size(); j++) {
for(auto q: dp[i]) {
if(dp[j].find(k-q.f)!=dp[j].end())
ans = min(ans,q.s+dp[j][k-q.f]);
}
}
}
//cout << dp.size() << endl;
for(auto i: edges[centroid]) {
if(!centroids[i.f])
ans = min(ans,solve(i.f,sizes[i.f]));
}
return ans;
}
int best_path(int N, int K, int H[][2], int L[]){
n = N;
k = K;
edges.resize(n);
sizes.resize(n);
centroids.resize(n);
pair<ll,ll> in[n];
ll len[n];
for(int i = 0; i<n-1; i++) {
in[i].f = H[i][0]; in[i].s = H[i][1]; len[i] = L[i];
edges[in[i].f].emplace_back(in[i].s,len[i]);
edges[in[i].s].emplace_back(in[i].f,len[i]);
}
ll _ = solve(0,n);
if(_ == inf)
_ =-1;
return _;
}
/*
int main() {
cin >> n >> k;
edges.resize(n);
sizes.resize(n);
centroids.resize(n);
pair<int,int> in[n];
int len[n];
for(int i = 0; i<n-1; i++) {
cin >> in[i].f >> in[i].s >> len[i];
edges[in[i].f].emplace_back(in[i].s,len[i]);
edges[in[i].s].emplace_back(in[i].f,len[i]);
}
auto _ = solve(0);
if(_ == inf)
_ =-1;
cout << _;
}*/
