// looking to shine brighter in this world...
#define TASK "race"
#include "race.h"
#ifdef LOCAL
#include "local.h"
#else
#include <bits/stdc++.h>
#define debug(...)
#define DB(...)
#endif
using namespace std;
using ll = long long;
using ld = long double;
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define fi first
#define se second
#define For(i, l, r) for (int i = (l); i <= (r); ++i)
#define Ford(i, r, l) for (int i = (r); i >= (l); --i)
#define Rep(i, n) For (i, 0, (n) - 1)
#define Repd(i, n) Ford (i, (n) - 1, 0)
#define Fe(...) for (auto __VA_ARGS__)
template <class C> inline int isz(const C& c) { return static_cast<int>(c.size()); }
template <class T> inline bool chmin(T& a, const T& b) { return (a > b) ? a = b, true : false; }
template <class T> inline bool chmax(T& a, const T& b) { return (a < b) ? a = b, true : false; }
const bool __initialization = []() {
cin.tie(nullptr)->sync_with_stdio(false);
if (fopen(TASK".inp", "r")) {
(void)(!freopen(TASK".inp", "r", stdin));
(void)(!freopen(TASK".out", "w", stdout)); }
cout << setprecision(12) << fixed;
return true;
}();
constexpr ld eps = 1e-9;
constexpr int inf = 0x3f3f3f3f; // for memset
constexpr ll linf = 1e18;
// ================================================================================
constexpr int maxn = 2e5;
constexpr int maxk = 100 + 1; // subtask 3
struct Info { int v, c; };
vector<Info> g[maxn];
int dp1[maxn][maxk];
void DfsDown(int u, int p, int k) {
dp1[u][0] = 0;
Fe (&[v, c] : g[u]) {
if (v == p) continue;
DfsDown(v, u, k);
For (i, 0, k - c) {
chmin(dp1[u][i + c], dp1[v][i] + 1);
}
}
}
int dp2[maxn][maxk];
void DfsUp(int u, int p, int k) {
vector<int> fi(k + 1, inf);
vector<int> se(k + 1, inf);
Fe (&[v, c] : g[u]) {
if (v == p) continue;
For (i, 0, k - c) {
if (fi[i + c] > dp1[v][i] + 1) {
se[i + c] = fi[i + c];
fi[i + c] = dp1[v][i] + 1;
}
else {
chmin(se[i + c], dp1[v][i] + 1);
}
}
}
Fe (&[v, c] : g[u]) {
if (v == p) continue;
dp2[v][0] = 0;
For (i, 0, k - c) {
chmin(dp2[v][i + c], dp2[u][i] + 1);
}
// TODO: optimize this
// Fe (&[w, cw] : g[u]) {
// if (w == p || w == v) continue;
// For (i, 0, k - c - cw) {
// chmin(dp2[v][i + c + cw], dp1[w][i] + 2);
// }
// }
For (i, c, k - c) {
int temp = (dp1[v][i - c] + 1 == fi[i]
? se[i]
: fi[i]);
chmin(dp2[v][i + c], temp + 1);
}
DfsUp(v, u, k);
}
}
int best_path(int n, int k, int h[][2], int l[]) {
Rep (i, n - 1) {
int u = h[i][0];
int v = h[i][1];
int c = l[i];
g[u].push_back({ v, c });
g[v].push_back({ u, c });
}
memset(dp1, 0x3f, sizeof(dp1));
DfsDown(0, -1, k);
memset(dp2, 0x3f, sizeof(dp2));
dp2[0][0] = 0;
DfsUp(0, -1, k);
int ans = inf;
Rep (u, n) {
For (i, 0, k) {
chmin(ans, dp1[u][i] + dp2[u][k - i]);
}
}
if (ans == inf) ans = -1;
return ans;
}
