#include<bits/stdc++.h>
#include "race.h"
#define maxn 200005
//#define MAX_N 500000
using namespace std;
int n,k;
vector<pair<int,int> > a[maxn]; //u a[u] su grane susedne sa u
set<pair<int,int> > s[maxn];
int o1[maxn];
int o2[maxn];
int pok[maxn];
int sol;
void dfs(int u,int pr) {
pok[u] = u;
s[u].insert({0,0});
o1[u] = 0;
o2[u] = 0;
int ch = 0;
for(auto edge:a[u]) {
int v=edge.first;
int w=edge.second;
if(v!=pr) {
ch++;
dfs(v,u);
if(s[pok[u]].size()<=s[pok[v]].size()) pok[u]=pok[v];
}
}
if(ch==0) {
return;
}
for(auto edge:a[u]) {
int v=edge.first;
int l=edge.second;
if(v!=pr) {
if(pok[u]==pok[v]) {
o1[pok[u]]+=l;
o2[pok[u]]+=1;
}
}
}
s[pok[u]].insert({-o1[pok[u]],-o2[pok[u]]});
set<pair<int,int> >::iterator it = s[pok[u]].lower_bound({k-o1[pok[u]],-1e9});
if(it!=s[pok[u]].end() && (*it).first==k-o1[pok[u]]) sol=min(sol,(*it).second+o2[pok[u]]);
for(auto edge:a[u]) {
int v=edge.first;
int l=edge.second;
if(v!=pr && pok[v]!=pok[u]) {
for(auto val:s[pok[v]]) {
int d = val.first + o1[pok[v]];
int i = val.second + o2[pok[v]];
set<pair<int,int> >::iterator it = s[pok[u]].lower_bound({k-d-l-o1[pok[u]],-1e9});
if(it!=s[pok[u]].end() && (*it).first==k-d-l-o1[pok[u]]) sol=min(sol,(*it).second+o2[pok[u]]+i+1);
}
for(auto val:s[pok[v]]) {
int d = val.first + o1[pok[v]];
int i = val.second + o2[pok[v]];
s[pok[u]].insert({d+l-o1[pok[u]],i+1-o2[pok[u]]});
//set<pair<int,int> >::iterator it = s[pok[u]].lower_bound({k-d-l-o1[pok[u]],-1e9});
//if(it!=s[pok[u]].end() && (*it).first==k-d-l-o1[pok[u]]) sol=min(sol,(*it).second+o2[pok[u]]+i+1);
}
}
}
}
int best_path(int N, int K, int H[][2], int L[]) {
n=N;
k=K;
for(int i=0;i<n-1;i++) {
a[H[i][0]].push_back({H[i][1],L[i]});
a[H[i][1]].push_back({H[i][0],L[i]});
}
sol=1e9;
dfs(0,-1);
if(sol==1e9) return -1;
else return sol;
}
/*static int N, K;
static int H[MAX_N][2];
static int L[MAX_N];
void read_input()
{
int i;
scanf("%d %d",&N,&K);
for(i=0; i<N-1; i++)
scanf("%d %d %d",&H[i][0],&H[i][1],&L[i]);
}
int main()
{
int ans;
read_input();
ans = best_path(N,K,H,L);
printf("%d",ans);
return 0;
}*/
