//
// Created by 42kangaroo on 17/01/2023.
//
#include <bits/stdc++.h>
using namespace std;
#define int long long
struct Edge {
int fr, to, w;
};
struct nEdge {
int to, w;
int stat;
};
bool operator>(const Edge &l, const Edge &r) {
return l.w > r.w;
}
bool operator>(const nEdge &l, const nEdge &r) {
return l.w > r.w;
}
using g_t = vector<vector<Edge>>;
void dfs(int n, g_t &gr, g_t &outB, g_t &outF, vector<bool>& vis) {
if (vis[n])return;
vis[n] = true;
for (auto e: gr[n]) {
outB[n].push_back(e);
outF[e.to].push_back({e.to, e.fr, 0});
dfs(e.to, gr, outB, outF, vis);
}
}
g_t dijkstra(g_t &gr, int s, int t) {
vector<int> dist(gr.size(), -1);
priority_queue<Edge, vector<Edge>, greater<>> q;
q.push({s, s, 0});
g_t back(gr.size());
while (!q.empty()) {
auto ed = q.top();
q.pop();
if (dist[ed.to] != -1 && dist[ed.to] < ed.w) continue;
back[ed.to].push_back({ed.to, ed.fr, 0});
if (dist[ed.to] == -1) {
dist[ed.to] = ed.w;
for (auto &e: gr[ed.to]) {
auto ne = e;
ne.w = ed.w + e.w;
q.push(ne);
}
}
}
return back;
}
int dijkstradist(g_t &gr, g_t &ba, g_t &fr, int u, int v) {
array<vector<int>, 4> d{};
d.fill(vector<int>(gr.size(), -1));
priority_queue<nEdge, vector<nEdge>, greater<>> q;
q.push({u, 0, 0});
while (!q.empty()) {
auto ed = q.top();
q.pop();
if (ed.to == v) {
return ed.w;
}
if (d[ed.stat][ed.to] != -1) continue;
d[ed.stat][ed.to] = ed.w;
for (auto e: gr[ed.to]) {
if (ed.stat == 0) {
q.push({e.to, e.w + ed.w, 0});
} else {
q.push({e.to, e.w + ed.w, 3});
}
}
if (ed.stat < 2) {
for (auto e: fr[ed.to]) {
q.push({e.to, e.w + ed.w, 1});
}
}
if (!(ed.stat & 1)) {
for (auto e: ba[ed.to]) {
q.push({e.to, e.w + ed.w, 2});
}
}
}
return -1;
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n, m, s, t, u, v;
cin >> n >> m >> s >> t >> u >> v;
--s;
--t;
--u;
--v;
g_t gr(n);
for (int i = 0; i < m; ++i) {
int a, b, c;
cin >> a >> b >> c;
--a;
--b;
gr[a].push_back({a, b, c});
gr[b].push_back({b, a, c});
}
auto back = dijkstra(gr, s, t);
g_t backR(n), frontR(n);
vector<bool> vis(n, false);
dfs(t, back, backR, frontR, vis);
cout << dijkstradist(gr, backR, frontR, u, v) << "\n";
}
