#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define sort undefined_function // To use stable_sort instead sort
#define bpc __builtin_popcount
#define ull unsigned long long
#define ld double
#define ll long long
#define mp make_pair
#define F first
#define S second
#pragma GCC optimize("O3")
#ifdef LOCAL
#include "debug.h"
#else
#define dbg(...) 0
#endif
using namespace __gnu_pbds;
using namespace std;
typedef tree<long long, null_type, less_equal<long long>,
rb_tree_tag, tree_order_statistics_node_update> Tree;
const ll INF = 9223372036854775807LL;
const ll inf = 2147483647;
const ll MOD = 1e9 + 7; //[998244353, 1e9 + 7, 1e9 + 13]
const ld PI = acos(-1);
const ll NROOT = 500;
ll binpow(ll a, ll b, ll _MOD = -1) {
if (_MOD == -1)
_MOD = MOD;
ll res = 1;
for (; b; b /= 2, a *= a, a %= _MOD)
if (b & 1) res *= a, res %= _MOD;
return res;
}
void set_IO(string s) {
#ifndef LOCAL
string in = s + ".in";
string out = s + ".out";
freopen(in.c_str(), "r", stdin);
freopen(out.c_str(), "w", stdout);
#endif
}
bool dataOverflow(ll a, ll b) {return (log10(a) + log10(b) >= 18);}
ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;}
ll lcm(ll a, ll b) {return a * b / gcd(a, b);}
ll ceil(ll a, ll b) {return (a + b - 1) / b;}
ll invmod(ll a) {return binpow(a, MOD - 2);}
#define int long long
int n, m;
vector<vector<pair<int, ll>>> g;
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> m;
g.resize(n + 1);
int s, t, u, v;
cin >> s >> t >> u >> v;
vector<pair<pair<int, int>, ll>> edges;
map<pair<int, int>, int> ID, old;
for (int i = 1; i <= m; i ++) {
int a, b; ll c;
cin >> a >> b >> c;
ID[{b, a}] = ID[{a, b}] = edges.size();
old[{b, a}] = old[{a, b}] = c;
edges.push_back({{a, b}, c});
g[a].push_back({b, c});
g[b].push_back({a, c});
}
using T = pair<ll, int>;
priority_queue<T, vector<T>, greater<T>> q;
q.push({0, s});
vector<ll> dis(n + 1, INF);
while (!q.empty()) {
auto [d, x] = q.top();
q.pop();
if (dis[x] <= d)
continue;
dis[x] = d;
for (auto &y : g[x])
q.push({d + y.S, y.F});
}
vector<bool> vis(n + 1);
q.push({dis[t], t});
while (!q.empty()) {
auto [d, x] = q.top();
q.pop();
if (vis[x])
continue;
vis[x] = 1;
for (auto &y : g[x]) {
if (dis[y.F] + y.S == dis[x]) {
q.push({dis[y.F], y.F});
edges[ID[{x, y.F}]].S = 0;
}
}
}
vector<vector<pair<int, ll>>> g1(n + 1), g2(n + 1);
for (auto &x : edges) {
auto [a, b] = x.F;
ll c = x.S;
if (c == 0) {
dbg(a, b);
if (dis[a] < dis[b]) {
g1[a].push_back({b, 0});
g1[b].push_back({a, old[{a, b}]});
g2[b].push_back({a, 0});
g2[a].push_back({b, old[{a, b}]});
} else {
g1[b].push_back({a, 0});
g1[a].push_back({b, old[{a, b}]});
g2[a].push_back({b, 0});
g2[b].push_back({a, old[{a, b}]});
}
} else {
g1[a].push_back({b, c});
g1[b].push_back({a, c});
g2[a].push_back({b, c});
g2[b].push_back({a, c});
}
}
vector<ll> dis1(n + 1, INF), dis2(n + 1, INF);
q.push({0, u});
while (!q.empty()) {
auto [d, x] = q.top();
q.pop();
if (dis1[x] <= d)
continue;
dis1[x] = d;
for (auto &y : g1[x])
q.push({d + y.S, y.F});
}
q.push({0, u});
while (!q.empty()) {
auto [d, x] = q.top();
q.pop();
if (dis2[x] <= d)
continue;
dis2[x] = d;
for (auto &y : g2[x])
q.push({d + y.S, y.F});
}
if (dis1[v] == INF && dis2[v] == INF) {
cout << "-1\n";
} else {
cout << min(dis1[v], dis2[v]) << "\n";
}
return 0;
}
