#include <bits/stdc++.h>
using namespace std;
using ll = long long;
vector<ll> diji(int n, int src, int t, vector<vector<pair<ll, ll>>> &adj) {
priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>> pq;
vector<ll> dist(n + 1, 2e18);
vector<ll> p(n + 1, -1);
dist[src] = 0;
pq.push({0, src});
while (!pq.empty()) {
ll d = pq.top().first;
ll u = pq.top().second;
pq.pop();
if (dist[u] < d) continue;
for (auto e : adj[u]) {
ll v = e.first;
ll wt = e.second;
if (dist[v] > d + wt) {
dist[v] = d + wt;
p[v] = u;
pq.push({dist[v], v});
}
}
}
vector<ll> pa;
if (dist[t] == 2e18) return pa;
ll cur = t;
while (cur != -1) {
pa.push_back(cur);
cur = p[cur];
}
std::reverse(pa.begin(), pa.end());
return pa;
}
ll diji2(int n, int src, int t, vector<vector<pair<ll, ll>>> &adj) {
priority_queue<pair<ll, ll>, vector<pair<ll, ll>>, greater<pair<ll, ll>>> pq;
vector<ll> dist(n + 1, 2e18);
dist[src] = 0;
pq.push({0, src});
while (!pq.empty()) {
ll d = pq.top().first;
ll u = pq.top().second;
pq.pop();
if (dist[u] < d) continue;
for (auto e : adj[u]) {
ll v = e.first;
ll wt = e.second;
if (dist[v] > d + wt) {
dist[v] = d + wt;
pq.push({dist[v], v});
}
}
}
return dist[t];
}
int main() {
int n, m;
cin >> n >> m;
int s, t;
cin >> s >> t;
int u, v;
cin >> u >> v;
vector<vector<pair<ll, ll>>> adj(n + 1);
for (int i = 0; i < m; i++) {
int a, b, c;
cin >> a >> b >> c;
// Bi-directional: add both ways
adj[a].push_back({(ll)b, (ll)c});
adj[b].push_back({(ll)a, (ll)c});
}
vector<ll> path = diji(n, s, t, adj);
if (!path.empty()) {
for (int i = 1; i < (int)path.size(); i++) {
adj[path[i - 1]].push_back({path[i], 0});
adj[path[i]].push_back({path[i - 1], 0});
}
}
ll result = diji2(n, u, v, adj);
if (result >= 2e18) cout << -1 << endl;
else cout << result << endl;
return 0;
}
