#include <iostream>
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <string>
#include <cmath>
#include <set>
#include <queue>
#include <map>
#include <climits>

using namespace std;

typedef long long int ll;
typedef double de;

const ll INF = LLONG_MAX;

#define mp(x,y) pair<int,int>(x,y)

int main()
{
        ios_base::sync_with_stdio(false);
        ifstream cin("distance.in");
        ofstream cout("distance.out");
        int n,m,f,s;
        cin >> n >> m >> s >> f;s--,f--;
        vector<vector<pair<int,int> > > g(n);
        vector<ll> d(n,INF),p(n);
        for(int i = 0;i < m;i++)
        {
                int a,b,c;
                cin >> a >> b >> c;a--,b--;
                g[a].push_back(mp(b,c));
                g[b].push_back(mp(a,c));
        }
        priority_queue<pair<int,int> > q;
        q.push(mp(0,s));
        d[s] = 0;
        while(!q.empty())
        {
                int v = q.top().second, dis = -q.top().first;
                q.pop();
                if(d[v] < dis) continue;
                for(int i = 0;i < g[v].size();i++)
                {
                        int to = g[v][i].first,len = g[v][i].second;
                        if(d[to] > d[v] + len)
                        {
                                d[to] = d[v] + len;
                                p[to] = v;
                                q.push(mp(-d[to],to));
                        }
                }
        }
        if(d[f] == INF) {cout << -1 << endl;return 0;}
        vector<int> path;
        for(int i = f;i != s;i = p[i])
                path.push_back(i);
        path.push_back(s);
        cout << d[f] << endl;
        for(int i = path.size()-1;i >= 0;i--)
                cout << path[i]+1 << " ";
        cout << endl;
    return 0;
}