#include "race.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define ff(i,a,b) for(int i=a;i<=b;i++)
#define fb(i,b,a) for(int i=b;i>=a;i--)
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair<ll,int> pii;
const int maxn = 200005;
const int inf = 1e9 + 5;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k) print the k-th smallest number in os(0-based)
int n, K;
vector<pii> g[maxn];
int cnt[maxn];
bool bio[maxn];
void dfs_sz(int v, int p) {
cnt[v] = 1;
for(auto c : g[v]) {
int u = c.fi;
int w = c.se;
if(u == p || bio[u])continue;
dfs_sz(u, v);
cnt[v] += cnt[u];
}
}
int centroid(int v, int p, int vel) {
for(auto c : g[v]) {
int u = c.fi;
int w = c.se;
if(u == p || bio[u])continue;
if(cnt[u] > vel / 2)return centroid(u, v, vel);
}
return v;
}
int rez = inf;
const int N = (int)1e6;
int kol[N + 5];
vector<pii> cuvaj;
void dfs_calc(int v, int p, int W, int duz) {
if(W > K)return;
cuvaj.pb({W, duz});
if(kol[K - W] != inf)rez = min(rez, kol[K - W] + duz);
for(auto c : g[v]) {
int u = c.fi;
int w = c.se;
if(u == p || bio[u])continue;
dfs_calc(u, v, W + w, duz + 1);
}
}
void decompose(int v, int p) {
dfs_sz(v, p);
int cen = centroid(v, p, cnt[v]);
bio[cen] = 1;
cuvaj.clear();
kol[0] = 0;
vector<int> brisi;
for(auto c : g[cen]) {
int u = c.fi;
int w = c.se;
if(u == p || bio[u])continue;
dfs_calc(u, cen, w, 1);
for(auto c : cuvaj) {
kol[c.fi] = min(kol[c.fi], c.se);
brisi.pb(c.fi);
}
}
for(auto c : brisi)kol[c] = inf;
for(auto c : g[cen]) {
int u = c.fi;
int w = c.se;
if(u == p || bio[u])continue;
decompose(u, cen);
}
}
int best_path(int N, int k, int H[][2], int L[]) {
n = N;
K = k;
ff(i,0,n - 2) {
int u = H[i][0] + 1;
int v = H[i][1] + 1;
int w = L[i];
g[u].pb({v, w});
g[v].pb({u, w});
}
ff(i,1,N)kol[i] = inf;
decompose(1, -1);
return (rez == inf ? -1 : rez);
}
//int main()
//{
// ios::sync_with_stdio(false);
// cout.tie(nullptr);
// cin.tie(nullptr);
// cin >> n >> K;
// ff(i,1,n - 1){
// int u, v, w;
// cin >> u >> v >> w;
// g[u].pb({v, w});
// g[v].pb({u, w});
// }
//
// ff(i,1,N)kol[i] = inf;
// decompose(1, -1);
//
// cout << (rez == inf ? -1 : rez) << endl;
//
// return 0;
//}
/**
3 3
1 2 1
2 3 1
11 12
1 2 3
1 3 4
3 4 5
4 5 4
5 6 6
1 7 3
7 8 2
7 9 5
9 10 6
9 11 7
// probati bojenje sahovski ili slicno
**/
