#include <bits/stdc++.h>
#include "cyberland.h"
// #include "stub.cpp"
using namespace std;
#define ff first
#define ss second
#define pii pair<int, int>
double solve(int n, int M, int K, int H, vector<int> X, vector<int> Y, vector<int> C, vector<int> a) {
vector<pii> E[n];
for (int i = 0; i < M; i++) {
E[X[i]].push_back({Y[i], C[i]});
E[Y[i]].push_back({X[i], C[i]});
}
queue<int> q;
vector<bool> vis0(n);
q.push(0); vis0[0] = true;
while (!q.empty()) {
int x = q.front(); q.pop();
if (x == H) continue;
for (auto [i, w] : E[x]) {
if (!vis0[i]) {
q.push(i);
vis0[i] = true;
}
}
}
if (!vis0[H]) return -1;
K = min(K, 66);
vector<vector<double>> dis(n, vector<double>(K + 1, 1e18));
priority_queue<pair<double, int>> pq;
for (int i = 0; i < n; i++) {
if (!i || (!a[i] && vis0[i])) {
dis[i][0] = 0;
pq.push({0, 70 * i});
}
}
while (!pq.empty()) {
auto [d, x] = pq.top(); d = -d; pq.pop();
int y = x % 70; x /= 70;
if (d != dis[x][y]) continue;
if (x == H) continue;
for (auto [i, w] : E[x]) {
if (!a[i]) continue;
if (d + w < dis[i][y]) {
dis[i][y] = d + w;
pq.push({-dis[i][y], y + 70 * i});
}
if (a[i] == 2 && y < K && (d + w) / 2 < dis[i][y + 1]) {
dis[i][y + 1] = (d + w) / 2;
pq.push({-dis[i][y + 1], y + 1 + 70 * i});
}
}
}
return *min_element(dis[H].begin(), dis[H].end());
}
