#include <iostream>
#include <queue>
#include <vector>
#define int long long
const int MAX_SOMMET = 1e5+42, INF = 1e16;
using namespace std;
struct Arete{
int dest, cost;
bool operator<(const Arete &autre) const {
return cost > autre.cost;
}
};
int nbSommet, nbArete;
int departPcc, arrivePcc, depart, arrive;
vector<Arete> adj[MAX_SOMMET];
void input() {
cin >> nbSommet >> nbArete >> departPcc >> arrivePcc >> depart >> arrive;
departPcc--; arrivePcc--; depart--; arrive--;
for(int arete = 0; arete < nbArete; arete++) {
int u,v,c;
cin >> u >> v >> c;
u--; v--;
adj[u].push_back({v, c});
adj[v].push_back({u, c});
}
}
int dist[MAX_SOMMET];
bool vuPcc[MAX_SOMMET] = {0};
bool sommetPcc[MAX_SOMMET] = {0};
void calcPcc() {
priority_queue<Arete> q;
q.push({departPcc, 0});
while(!q.empty()) {
Arete cur = q.top();
q.pop();
if(vuPcc[cur.dest])
continue;
vuPcc[cur.dest] = 1;
dist[cur.dest] = cur.cost;
for(auto voisin : adj[cur.dest]) {
q.push({voisin.dest, cur.cost + voisin.cost});
}
}
queue<int> marque;
marque.push(arrivePcc);
while(!marque.empty()) {
int cur = marque.front();
marque.pop();
sommetPcc[cur] = 1;
for(auto voisin : adj[cur]) {
if(dist[cur] - dist[voisin.dest] == voisin.cost) {
marque.push(voisin.dest);
}
}
}
}
struct Situation{
int sommet, dist, prisPass;
bool croissant;
bool operator<(const Situation &autre) const {
return dist > autre.dist;
}
};
int reponse[MAX_SOMMET][3][2];
bool vu[MAX_SOMMET][3][2];
bool correct(int a, int b, int c) {
return (a < b && c) || (b < a && !c);
}
void calcRep() {
for(int i = 0; i < MAX_SOMMET; i++) {
for(int j = 0; j < 3; j++) {
reponse[i][j][0] = reponse[i][j][1] = INF;
}
}
priority_queue<Situation> q;
q.push({depart, 0, sommetPcc[depart], 0});
q.push({depart, 0, sommetPcc[depart], 1});
while(!q.empty()) {
int cur = q.top().sommet, pass = q.top().prisPass, curDist = q.top().dist, crois = q.top().croissant;
q.pop();
if(vu[cur][pass][crois])
continue;
vu[cur][pass][crois] = 1;
reponse[cur][pass][crois] = curDist;
for(auto voisin : adj[cur]) {
if(pass == 2) {
q.push({voisin.dest, curDist + voisin.cost, pass, crois});
}
else if(pass == 0) {
q.push({voisin.dest, curDist + voisin.cost, sommetPcc[voisin.dest], crois});
}
else {
if(sommetPcc[voisin.dest] && correct(dist[cur], dist[voisin.dest], crois)) {
q.push({voisin.dest, curDist, 1, crois});
}
else {
q.push({voisin.dest, curDist + voisin.cost, 2, crois});
}
}
}
}
}
signed main() {
input();
calcPcc();
calcRep();
int rep = INF;
for(int i = 0; i < 3; i++) {
rep = min(rep, min(reponse[arrive][i][0], reponse[arrive][i][1]));
}
if(rep == INF) {
cout << -1;
return 0;
}
cout << rep;
}
