#include <bits/stdc++.h>
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){
std::vector<std::vector<std::pair<long long , long long>>> adj(N);
for(int i = 0; i < M ; i++) adj[x[i]].push_back({y[i],c[i]});
for(int i = 0; i < M ; i++) adj[y[i]].push_back({x[i],c[i]});
std::vector<long double> dist(N,-1);
std::priority_queue<std::pair<long double,long long>> pq;
dist[0]=0;
pq.push({0,0});
while(!pq.empty()){
std::pair<long double,long long> nd = pq.top(); pq.pop();
nd.first*=-1;
if(dist[nd.second]<nd.first&&dist[nd.second]!=-1) continue;
//std::cout<<nd.first<<" "<<nd.second<<'\n';
for(auto dat:adj[nd.second]){
if(dist[dat.first]>dist[nd.second]+dat.second||dist[dat.first]==-1){
dist[dat.first]=dist[nd.second]+dat.second;
pq.push({dist[dat.first]*-1,dat.first});
}
}
}
return dist[H];
}
