#include <bits/stdc++.h>
#define ii pair<int, int>
#define lli pair<long long, int>
#define fi first
#define se second
#define all(v) begin(v), end(v)
#define dbg(x) "[" #x " = " << x << "]"
using namespace std;
const int MAXN = 1e5 + 5;
template<class X, class Y>
bool minimize(X &x, const Y &y){
if (x > y){
x = y; return 1;
}
return 0;
}
template<class X, class Y>
bool maximize(X &x, const Y &y){
if (x < y){
x = y; return 1;
}
return 0;
}
struct edge{
int u, v, w;
edge(int _u = 0, int _v = 0, int _w = 0):
u(_u), v(_v), w(_w) {};
int other(int x){
return u ^ v ^ x;
}
};
int numNode, numEdge, staX, finX, staY, finY, par[MAXN];
long long dist[MAXN];
vector<int> adj[MAXN], nadj[MAXN];
edge e[MAXN << 1];
void dijsktra(int sta, int fin){
priority_queue<lli, vector<lli>, greater<lli>> q;
memset(dist, 0x3f, sizeof dist);
q.push(lli(dist[sta] = 0, sta));
int cnt = 0;
while(q.size()){
int u = q.top().se;
long long len = q.top().fi;
q.pop();
if (len > dist[u]) continue;
for(int id: adj[u]){
int v = e[id].other(u);
if (minimize(dist[v], dist[u] + e[id].w)) q.push(lli(dist[v], v));
}
}
}
void bfs(int sta, int fin){
queue<int> q;
memset(dist, -0x3f, sizeof dist);
q.push(sta); dist[sta] = 0;
while(q.size()){
int u = q.front(); q.pop();
for(int id: nadj[u]){
int v = e[id].other(u);
if (maximize(dist[v], dist[u] + 1)) q.push(v), par[v] = id;
}
}
while(fin != sta){
e[par[fin]].w = 0;
fin = e[par[fin]].other(fin);
}
}
void input(){
cin >> numNode >> numEdge >> staX >> finX >> staY >> finY;
for(int i = 1; i <= numEdge; i++){
cin >> e[i].u >> e[i].v >> e[i].w;
adj[e[i].u].push_back(i);
adj[e[i].v].push_back(i);
}
}
void solve(){
dijsktra(staX, finX);
for(int id = 1; id <= numEdge; id++){
if (dist[e[id].u] == dist[e[id].v] + e[id].w){
nadj[e[id].v].push_back(id);
}else if (dist[e[id].v] == dist[e[id].u] + e[id].w){
nadj[e[id].u].push_back(id);
}
}
bfs(staX, finX);
dijsktra(staY, finY);
cout << dist[finY] << '\n';
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
input();
solve();
}
