#include "cyberland.h"
#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
using ll = int;
using P = pair<double,int>;
const ll mod = 998244353;
#define fi first
#define se second
#define rep(i,n) for(ll i=0;i<n;i++)
#define all(x) x.begin(),x.end()
#define faster ios::sync_with_stdio(false);cin.tie(nullptr)
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<double> dis(N,1e15);
double ans=1e15;
dis[0]=0;
vector<vector<pair<int,int>>> G(N);
rep(i,M){
G[x[i]].push_back({y[i],i});
G[y[i]].push_back({x[i],i});
}
rep(loop,100){
priority_queue<P,vector<P>,greater<P>> pq;
rep(i,N) pq.emplace(dis[i],i);
while(!pq.empty()){
P p=pq.top();
pq.pop();
int v=p.se;
if(p.fi>dis[v]) continue;
if(p.fi==1e15) continue;
if(v==H) continue;
for(auto &e:G[v]){
double cost=dis[v]+c[e.se];
if(arr[e.fi]==0) cost=0;
if(dis[e.fi]>cost){
dis[e.fi]=cost;
pq.emplace(dis[e.fi],e.fi);
}
}
}
ans=min(ans,dis[H]);
dis[H]=1e15;
vector<double> next_dis(N,1e15);
if(loop<K) rep(i,M){
if(arr[x[i]]==2) if(dis[y[i]]<1e15) next_dis[x[i]]=min(next_dis[x[i]],(dis[y[i]]+c[i])/2);
if(arr[y[i]]==2) if(dis[x[i]]<1e15) next_dis[y[i]]=min(next_dis[y[i]],(dis[x[i]]+c[i])/2);
}
rep(i,N){
dis[i]=min(dis[i],next_dis[i]);
}
ans=min(ans,dis[H]);
dis[H]=1e15;
}
if(ans==1e15) return -1;
return ans;
}
