#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
const double inf = 1e30;
double solve(int N, int M, int K, int H, vector<int> x, vector<int> y, vector<int> c, vector<int> arr){
double ans = 1e30;
K = min(K, 70);
vector<pair<int,int>> adj[N];
vector<vector<double>> dp(N, vector<double>(K+1, inf));
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]});
}
vector<int> a = arr;
priority_queue<tuple<double,int,int>, vector<tuple<double, int, int>>, greater<tuple<double,int,int>>> pq;
dp[0][0] = 0.0;
pq.push({0.0, 0,0});
while(!pq.empty()){
auto [c, u, pos] = pq.top(); pq.pop();
if(c > dp[u][pos]) continue;
for(auto &[v, w] : adj[u]){
double cost = c+w;
if(dp[v][pos] > cost){
dp[v][pos] = cost;
pq.push({cost, v, pos});
}
if(a[u] == 2 && pos < K){
double co = c+w/2.0;
if(dp[v][pos+1] > co){
dp[v][pos+1] = co;
pq.push({co, v, pos+1});
}
}
}
}
for(int i = 0; i <= K; i++) ans = min(ans, dp[H][i]);
return (ans >= inf/2 ? -1.0 : ans);
}
