#include <bits/stdc++.h>
#define endl '\n'
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define fo(i,n) for(auto i =0 ; i < n;i++)
#define fore(i,l,r) for(auto i = l; i < r;i++)
#define forex(i,r,l) for(auto i = r; i >= l; i--)
#define ffo(i,n) forex(i,n-1,0)
#define all(x) x.begin(),x.end()
#define lsb(x) x&(-x)
#define sz(x) (int)x.size()
#define gcd(a,b) __gcd(a,b)
#define vii vector<ii>
using namespace std;
using ll = long long; using ull = unsigned long long;
using vi = vector<int>;using ii = pair<int,int>;using mii = map<int,int>;
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#define state pair<double, pair<int,int>>
double solve(int N, int M, int K, int H, vi x, vi y, vi c, vi arr){
vector<vii> graph(N);
fo(i,M){graph[x[i]].pb({y[i], c[i]});graph[y[i]].pb({x[i], c[i]});}
vector<vector<double>> minDist(N+1, vector<double>(K+1,1e18));
vector<vector<bool>> vis(N+1, vector<bool>(K+1,0));
priority_queue<state, vector<state>, greater<state>> pq;
pq.push({0, {0, 0}});
while(!pq.empty()){
auto act = pq.top(); pq.pop();
if(vis[act.s.s][act.s.f] || act.s.s == H)continue;
// cout << act.s.s << " " << act.f << " " << act.s.f << endl;
vis[act.s.s][act.s.f] = 1;
for(auto [v,cost] : graph[act.s.s]){
double newcost = (double)act.f + (double)cost;
// no hacer nada
if(newcost < minDist[v][act.s.f]){
minDist[v][act.s.f] = newcost;
pq.push({newcost, {act.s.f, v}});
}
// usar el cupon
if(arr[v] == 2 and act.s.f + 1 <= K){
double othercost = newcost/(double)2;
if(othercost < minDist[v][act.s.f+1]){
minDist[v][act.s.f+1] = othercost;
pq.push({othercost, {act.s.f+1, v}});
}
}
// if(v==1)assert(arr[v]==0);
if(arr[v] == 0){
if(0<minDist[v][act.s.f]){
minDist[v][act.s.f] = 0;
pq.push({0, {act.s.f, v}});
}
}
}
}
double ans = 1e18;
fo(i,K+1)ans=min(ans,minDist[H][i]);
return ans;
}
