#include "cyberland.h"
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define foru(i, l, r) for(int i = l; i <= r; i++)
#define ford(i, r, l) for(int i = r; i >= l; i--)
#define __TIME (1.0 * clock() / CLOCKS_PER_SEC)
using vi = vector<int>;
using ar = pair<double, int>;
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;
typedef pair<double, int> ar;
const int N = 1e5 + 10;
const double oo = DBL_MAX;
int n, m, h;
double ans = 0;
bool vis[N];
double dis[N], dis2[N];
vector<ii> adj[N];
priority_queue<ar, vector<ar>, greater<ar>> pq;
void dijkstra() {
fill(vis, vis + n + 1, 0);
foru(i, 0, n - 1) if (dis[i] < oo) pq.push({dis[i], i});
while (!pq.empty()) {
auto tmp = pq.top(); pq.pop();
double D = tmp.fi; int a = tmp.se;
if (vis[a] || a == h) continue; vis[a] = 1;
for (auto tmp : adj[a]) {
int b = tmp.fi, w = tmp.se;
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, oo);
ans = oo;
foru(i, 0, n - 1) adj[i].clear();
foru(i, 0, m - 1) {
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] >= oo) return -1;
foru(i, 0, n - 1) if (dis[i] != oo) dis[i] = A[i] && i ? oo : 0;
foru(i, 0, K) {
dijkstra();
fill(dis2, dis2 + n, oo);
for (int j = 0; j < n; j++)
if (A[j] > 1) for (auto tmp : adj[j]) {
int u = tmp.fi, w = tmp.se;
dis2[u] = min(dis2[u], dis[j] / 2 + w);
}
for (int j = 0; j < n; j++) dis[j] = dis2[j];
}
return ans;
}
