#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
#include<stdio.h>
#include<stdlib.h>
#include<vector>
#include<map>
#define SUBMIT 1
const int inf = 2e9;
const int maxn = 2e5 + 5;
using namespace std;
///////////////////////////////////////////////////////////////////////////
//main code
vector<pair<int, int>> g[maxn];
int ans = inf, sub[maxn], found[maxn], n, k;
map<int, int> mp[maxn][2];
inline int cmin(int x, int y) { return min(x == 0 ? inf : x, y == 0 ? inf : y); }
void solve(int node, int par, int d, int dw, int c) {
mp[c][0][dw] = cmin(mp[c][0][dw], d);
if (dw == k) ans = min(ans, d);
if (mp[c][1].find(k - dw) != mp[c][1].end()) ans = min(ans, mp[c][1][k - dw] + d);
for (auto x : g[node])
if ((x.first != par) && (!found[x.first]))
solve(x.first, node, d + 1, dw + x.second, c);
}
int pre(int node, int par) {
sub[node] = 1;
for (const auto& x : g[node])
if ((x.first != par) && (!found[x.first]))
sub[node] += pre(x.first, node);
return sub[node];
}
void shift(int c) { for (auto x : mp[c][0]) mp[c][1][x.first] = cmin(mp[c][1][x.first], x.second); }
bool dfs(int node, int par, int cn) {
for (const auto &x : g[node])
if (((x.first == par ? -cn : sub[x.first]) > (cn / 2)) && !found[x.first])
return dfs(x.first, node, cn);
found[node] = 1; pre(node, 0);
for (auto x : g[node])
if (!found[x.first])
solve(x.first, node, 1, x.second, node),
shift(node), mp[node][0].clear(),
dfs(x.first, node, sub[x.first]);
mp[node][1].clear(); return 1;
}
int32_t best_path(int32_t N, int32_t K, int32_t h[][2], int32_t l[]) {
n = N, k = K;
for (int i = 0; i < (n - 1); ++i)
g[h[i][0] + 1].push_back({ h[i][1] + 1, l[i] }),
g[h[i][1] + 1].push_back({ h[i][0] + 1, l[i] });
pre(1, 0); dfs(1, 0, n);
return (int32_t)(ans == inf ? -1 : ans);
}
///////////////////////////////////////////////////////////////////////////
#if SUBMIT == 0
#define MAX_N 500000
static int32_t N, K;
static int32_t H[MAX_N][2];
static int32_t L[MAX_N];
static int32_t solution;
inline void my_assert(int e) { if (!e) abort(); }
void read_input() {
int i;
my_assert(2 == scanf("%d %d", &N, &K));
for (i = 0; i < N - 1; i++)
my_assert(3 == scanf("%d %d %d", &H[i][0], &H[i][1], &L[i]));
my_assert(1 == scanf("%d", &solution));
}
int32_t main() {
int ans;
read_input();
ans = best_path(N, K, H, L);
if (ans == solution)
printf("Correct.\n");
else
printf("Incorrect. Returned %d, Expected %d.\n", ans, solution);
return 0;
}
#endif
