#include "cyberland.h"
#include <bits/stdc++.h>
using namespace std;
using vi = vector<int>;
using ar = pair<double, int>;
const int mxN = 1e5 + 10;
const double LINF = 1e105;
double ans;
int n, m, h;
bool vis[mxN];
double dis[mxN], dis2[mxN];
vector<pair<int, int>> adj[mxN];
priority_queue<ar, vector<ar>, greater<ar>> pq;
void dijkstra() {
fill(vis, vis + n + 1, 0);
for (int i = 0; i < n; i++) if (dis[i] < LINF) pq.push({dis[i], i});
while (!pq.empty()) {
auto [D, a] = pq.top();
pq.pop();
if (vis[a] or a == h) continue;
vis[a] = 1;
for (auto [b, w] : adj[a]) if (dis[b] > dis[a] + w) dis[b] = dis[a] + w, pq.push({dis[b], b});
}
ans = min(ans, dis[h]);
}
double solve(int N, int M, int K, int H, vi x, vi y, vi c, vi A) {
n = N, m = M, h = H, K = min(K, 67);
fill(dis, dis + n, LINF);
ans = LINF;
for (int i = 0; i < n; i++) adj[i].clear();
for (int i = 0; i < m; i++) adj[x[i]].push_back({y[i], c[i]}), adj[y[i]].push_back({x[i], c[i]});
dis[0] = 0;
dijkstra();
if (dis[h] >= LINF) return -1;
for (int i = 0; i < n; i++) if (dis[i] != LINF) dis[i] = A[i] && i ? LINF : 0;
for (int i = 0; i <= K; i++) {
dijkstra();
fill(dis2, dis2 + n, LINF);
for (int j = 0; j < n; j++) if (A[j] > 1) for (auto [u, w] : adj[j]) dis2[u] = min(dis2[u], dis[j] / 2 + w);
for (int j = 0; j < n; j++) dis[j] = dis2[j];
}
return ans;
}
