#include "cyberland.h"
#include <bits/stdc++.h>
using namespace std;
const double INF = numeric_limits<double>::max();
double solve(int N, int M, int K, int H, std::vector<int> x, std::vector<int> y, std::vector<int> c, std::vector<int> arr) {
vector<vector<pair<int, int>>> g(N);
for (int i = 0; i < M; ++i) {
g[x[i]].emplace_back(y[i], c[i]);
g[y[i]].emplace_back(x[i], c[i]);
}
vector<bool> used(N), ot(N);
function<void(int, int)> dfs = [&](int v, int cnt) {
assert(!used[v]);
used[v] = true;
for (auto [to, weight]: g[v]) {
if (!used[to]) {
if (arr[to] == 2 && cnt) {
ot[to] = true;
dfs(to, cnt - 1);
} else dfs(to, cnt);
}
}
};
vector<double> d(N + 1, INF);
d[0] = 0;
set<pair<double, int>> q;
q.emplace(d[0], 0);
while (!q.empty()) {
int nearest = q.begin()->second;
q.erase(q.begin());
for (auto [to, weight]: g[nearest]) {
double dis = d[nearest] + weight;
if (ot[to]) dis /= 2;
if (!arr[to]) dis = 0;
if (d[to] > dis) {
q.erase(pair{d[to], to});
d[to] = dis;
q.emplace(d[to], to);
}
}
}
if (d[H] == INF) d[H] = -1;
return d[H];
}
