#include "bits/stdc++.h"
using namespace std;
#define int long long
const int N = 1e5 + 5;
#define II pair<int, int>
#define fi first
#define se second
int n, m;
int s, t, U, V;
vector<II> adj[N], adj2[N];
vector<int> parent[N];
int f[N], f2[N];
template<class X, class Y> bool mini(X &x, const Y y) {
if (x > y) return x = y, 1;
return 0;
}
void dijkstra(int start, int dist[], vector<II> g[], bool track_parents = false) {
fill(dist, dist + n + 1, LLONG_MAX);
priority_queue<II, vector<II>, greater<II>> pq;
pq.push({0, start});
dist[start] = 0;
while (!pq.empty()) {
II u = pq.top(); pq.pop();
if (u.fi != dist[u.se]) continue;
for (II v : g[u.se]) {
int new_dist = dist[u.se] + v.fi;
if (mini(dist[v.se], new_dist)) {
pq.push({dist[v.se], v.se});
if (track_parents) {
parent[v.se].clear();
parent[v.se].push_back(u.se);
}
} else if (dist[v.se] == new_dist && track_parents) {
parent[v.se].push_back(u.se);
}
}
}
}
void build_adj2() {
queue<int> q;
vector<bool> visited(n + 1, false);
q.push(t);
visited[t] = true;
while (!q.empty()) {
int u = q.front(); q.pop();
for (int v : parent[u]) {
adj2[u].push_back({0, v});
adj2[v].push_back({0, u});
if (!visited[v]) {
visited[v] = true;
q.push(v);
}
}
}
for (int i = 1; i <= n; i++) {
for (II j : adj[i]) {
if (f[i] + j.fi == f[j.se]) continue; // Already added as shortest path
adj2[i].push_back(j);
}
}
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m;
cin >> s >> t >> U >> V;
for (int i = 1; i <= m; i++) {
int u, v, c;
cin >> u >> v >> c;
adj[u].push_back({c, v});
adj[v].push_back({c, u});
}
dijkstra(s, f, adj, true);
build_adj2();
dijkstra(U, f2, adj2);
cout << (f2[V] == LLONG_MAX ? -1 : f2[V]) << "\n";
}
