#include "race.h"
#include<bits/stdc++.h>
//#define int long long
#define pii pair<int, int>
#define se second
#define fi first
#define ll long long
using namespace std;
const ll N1 = 2e5 + 5;
const ll MAXN = LLONG_MAX;
const ll mod = 1e9 + 7;
ll n, k;
ll sum[N1], ds[N1];
ll ans=MAXN;
pii a[N1];
map <ll, ll> dp[N1];
vector<vector <pii>> adj;
//int K, H[N1][2], L[N1], N;
void dfs(ll u, ll p) {
dp[u][sum[u]]=ds[u];
for (auto &i: adj[u]) {
if (i.fi==p) continue;
sum[i.fi]=sum[u]+i.se;
ds[i.fi]=ds[u]+1;
ll v;
dfs(v=i.fi, u);
if (dp[u].size() < dp[v].size()) swap(dp[u], dp[v]);
for (auto &j: dp[v]) {
if (dp[u].find(k+sum[u]*2-j.fi)!=end(dp[u])) {
ans=min(ans, dp[u][k+sum[u]*2-j.fi]+j.se-ds[u]*2);
}
}
for (auto &j: dp[v]) {
if (dp[u].find(j.fi)==end(dp[u])) {
dp[u][j.fi]=j.se;
}
else dp[u][j.fi]=min(dp[u][j.fi], j.se);
}
dp[v].clear();
}
}
int best_path(int N, int K, int H[][2], int L[]) {
n=N;
adj.resize(n);
for (int i=0; i<n-1; ++i) {
adj[H[i][0]].push_back({H[i][1], L[i]});
adj[H[i][1]].push_back({H[i][0], L[i]});
}
k=K;
dfs(0, 0);
if (ans==MAXN) return -1;
else return ans;
}
/*signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cin >> N >> K;
for (int i=0; i<N-1; ++i) {
cin >> H[i][0] >> H[i][1] >> L[i];
}
cout << best_path(N, K, H, L);
}*/
