// #include "cyberland.h"
#include <bits/stdc++.h>
using namespace std;
const int MAX = 1e7 + 6;
const int LOG = 25;
const int inf = 1e9;
const int mod = 1e9 + 7;
const int block = 333;
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
vector < double > d(MAX, inf);
vector < vector < pair < int , int > > > adj(MAX);
priority_queue < pair < int , int > , vector < pair < int , int > > , greater < pair < int , int > > > pq;
void djk(int s){
d[s] = 0;
pq.push({d[s], s});
while(pq.size()){
int w = pq.top().first;
int from = pq.top().second;
pq.pop();
if(w != d[from]) continue;
for(pair < int , int > p : adj[from]){
int we = p.first;
int to = p.second;
if(d[to] > d[from] + we){
d[to] = d[from] + we;
pq.push({d[to], to});
}
}
}
}
double solve(int N, int M, int K, int H, vector<int> x, vector<int> y, vector<int> c, vector<int> arr) {
int m = M, n = N, k = K, h = H;
for(int i = 0; i < m; i++){
adj[x[i]].push_back({c[i], y[i]});
adj[y[i]].push_back({c[i], x[i]});
}
djk(1);
double ans = d[h];
return (ans == inf ? -1 : ans);
}
