//BFS и алгоритм Дейкстры. Теория. Задача D.
#include <bits/stdc++.h>
using namespace std;
int n, m, start, finish;
vector < vector < pair < int , int > > > g;
vector < int > dist;
vector < int > from;

void Dijkstra() {
    dist.resize(n, 1e9 + 7);
    from.resize(n);
    from[start] = -1;
    dist[start] = 0;
    set < pair < int , int > > s;
    s.insert({0, start});
    while (!s.empty()) {
        auto c = *s.begin();
        s.erase(s.begin());
        int v = c.second;
        for (auto e : g[v]) {
            int u = e.first, d = e.second;
            if (dist[u] > dist[v] + d) {
                s.erase({dist[u], u});
                dist[u] = dist[v] + d;
                from[u] = v;
                s.insert({dist[u], u});
            }
        }
    }
}

void print_way() {
    if (dist[finish] == 1e9 + 7) {
        cout << -1;
        return;
    }
    cout << dist[finish] << endl;
    vector < int > vs;
    int v = finish;
    while (from[v] != -1) {
        vs.push_back(v);
        v = from[v];
    }
    vs.push_back(start);
    reverse(vs.begin(), vs.end());
    for (auto u : vs) cout << u + 1 << " " ;
}

int main() {
    cin >> n >> m;
    cin >> start >> finish;
    start--; finish--;
    g.resize(n);
    for (int i = 0; i < m; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        a--; b--;
        g[a].push_back({b, c});
        g[b].push_back({a, c});
    }
    Dijkstra();
    print_way();
    return 0;
}