#include "bits/stdc++.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
typedef long long ll;
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define all(c) (c).begin(), (c).end()
//#define int long long
#define pii pair<int,int>
#define pll pair<long long, long long>
#define sz(a) (int)a.size()
// permutation of the last layer
#define LOO(i,a,b) for (int i = a; i <= b; i++)
#define OOL(i,a,b) for (int i = b; i >= a; i--)
#define max3(a, b, c) max(max(a, b), c)
#define min3(a, b, c) min(min(a, b), c)
#define ld long double
// #pragma GCC optimize("Ofast")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC optimize("avx2")
using namespace std;
typedef tree<int,null_type, less_equal<>,rb_tree_tag,tree_order_statistics_node_update> ordered_multiset;
typedef tree<int,null_type, less<>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
constexpr ll MAX = 1e9+7;
void iO() {
freopen("haircut.out", "w",stdout);
freopen("haircut.in", "r",stdin);
}
vector<int> make_sorted_index(vector<auto> const &values) {
vector<int> index(values.size());
iota(index.begin(), index.end(), 0);
stable_sort(index.begin(), index.end(), [&values](auto a, auto b) {
return values[a] < values[b];
});
return index;
} // this function is so skibidi
struct chash {
static uint64_t splitmix64(uint64_t x) {
// http://xorshift.di.unimi.it/splitmix64.c
x += 0x9e3779b97f4a7c15;
x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
return x ^ (x >> 31);
}
size_t operator()(uint64_t x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
return splitmix64(x + FIXED_RANDOM);
}
int operator()(pii x) const {
static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();return splitmix64(FIXED_RANDOM * x.first + x.second + FIXED_RANDOM);
}
}; // gp_hash_table custom hash so skibid
vector<vector<pair<int, ll>>> graph;
void solve() {
int n, m, b1, e1, b2, e2;
cin>>n>>m>>b1>>e1>>b2>>e2;
b1--;e1--;b2--;e2--;
graph.resize(n);
LOO(i,0,m-1) {
int a,b,c;
cin>>a>>b>>c;a--;b--;
graph[a].PB(MP(b,c));
graph[b].PB(MP(a, c));
}
vector<ll> djkistrab1(n, -1);
vector<ll> djkistrae1(n, -1);
priority_queue<pair<ll, int>, vector<pair<ll, int>>, greater<>> skibidius;
skibidius.emplace(0, b1);
while (!skibidius.empty()) {
auto topp = skibidius.top();
skibidius.pop();
if (djkistrab1[topp.S]!=-1) continue;
djkistrab1[topp.S] = topp.F;
for (auto &child: graph[topp.S]) {
if (djkistrab1[child.F]!=-1) continue;
skibidius.push({topp.F+child.S, child.F});
}
}
skibidius.emplace(0, e1);
while (!skibidius.empty()) {
auto topp = skibidius.top();
skibidius.pop();
if (djkistrae1[topp.S]!=-1) continue;
djkistrae1[topp.S] = topp.F;
for (auto &child: graph[topp.S]) {
if (djkistrae1[child.F]!=-1) continue;
skibidius.push({topp.F+child.S, child.F});
}
}
ll shorty = djkistrab1[e1];
priority_queue<pair<ll, pair<int, int>>, vector<pair<ll, pair<int, int>>>, greater<>> sigma;
vector final_dj(4, vector<ll>(n, -1));
sigma.push({0, {b2, 0}});
while (!sigma.empty()) {
auto top = sigma.top();
sigma.pop();
if (final_dj[top.S.S][top.S.F]!=-1) continue;
final_dj[top.S.S][top.S.F] = top.F;
if (top.S.S==0) {
for (auto &child: graph[top.S.F]) {
if (final_dj[0][child.F]==-1) sigma.push({top.F+child.S, {child.F, 0}});
}
if (final_dj[2][top.S.F]==-1) sigma.push({top.F, {top.S.F, 2}});
if (final_dj[1][top.S.F]==-1) sigma.push({top.F, {top.S.F, 1}});
if (final_dj[3][top.S.F]==-1) sigma.push({top.F, {top.S.F, 3}});
}
else if (top.S.S==1 || top.S.S == 3) {
for (auto &child: graph[top.S.F]) {
if (final_dj[top.S.S][child.F]==-1) {
if (top.S.S==1) {
if (djkistrab1[child.F]+djkistrae1[top.S.F]+child.S==shorty) {
sigma.push({top.F, {child.F, 1}});
}
}
else {
if (djkistrab1[top.S.F]+djkistrae1[child.F]+child.S==shorty) {
sigma.push({top.F, {child.F, 3}});
}
}
}
}
if (final_dj[2][top.S.F]==-1) sigma.push({top.F, {top.S.F, 2}});
}
else {
for (auto &child: graph[top.S.F]) {
if (final_dj[2][child.F]==-1) sigma.push({top.F+child.S, {child.F, 2}});
}
}
}
cout << final_dj[2][e2] << '\n';
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// iO();
int t = 1;
//cin >> t;
while (t--) {
solve();
// cout << flush;
}
return 0;
}
