#include <bits/stdc++.h>
using namespace std;
#define pii pair<long long, int>
#define ll long long
const ll INF = 1e18;
const int MAXN = 1e5 + 5;
int N, M;
int S, T, U, V;
vector<tuple<int, int, int>> edges;
vector<pii> G[MAXN];
ll distS[MAXN], distT[MAXN], distU[MAXN];
// Dijkstra 從 start 開始
void dijkstra(int start, ll dist[]) {
priority_queue<pii, vector<pii>, greater<pii>> pq;
fill(dist, dist + N + 1, INF);
dist[start] = 0;
pq.push({0, start});
while (!pq.empty()) {
auto [d, u] = pq.top(); pq.pop();
if (d > dist[u]) continue;
for (auto [v, w] : G[u]) {
if (dist[v] > dist[u] + w) {
dist[v] = dist[u] + w;
pq.push({dist[v], v});
}
}
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> N >> M;
cin >> S >> T >> U >> V;
// 儲存邊，同時建立圖
for (int i = 0; i < M; ++i) {
int a, b, c;
cin >> a >> b >> c;
edges.emplace_back(a, b, c);
G[a].emplace_back(b, c);
G[b].emplace_back(a, c);
}
// 跑 Dijkstra 求 S -> all, T -> all
dijkstra(S, distS);
dijkstra(T, distT);
ll distST = distS[T];
// 清空圖準備重建
for (int i = 1; i <= N; ++i) G[i].clear();
// 找在 ST 最短路上的邊，設為 0，其他照原本
for (auto &[a, b, c] : edges) {
if (distS[a] + c + distT[b] == distST || distS[b] + c + distT[a] == distST) {
G[a].emplace_back(b, 0);
G[b].emplace_back(a, 0);
} else {
G[a].emplace_back(b, c);
G[b].emplace_back(a, c);
}
}
// 從 U 跑 Dijkstra 求最短距離到 V
dijkstra(U, distU);
// 輸出答案
if (distU[V] == INF) cout << -1 << '\n';
else cout << distU[V] << '\n';
return 0;
}
