#include <bits/stdc++.h>
using namespace std;

int n, m;
int s,t;


struct Edge {
    int u, v, w;
};

vector<Edge> adj[1010];

int dis[1010];
int vis[1010];
int path[1010];

struct Node {
    int v,d;
    bool operator < (const Node &a) const {
        return d > a.d;
    }
};


void dijkstra() {

    memset(dis, 0x3f, sizeof(dis));
    memset(vis, 0, sizeof(vis));

    priority_queue<Node> q;
    q.push({s, 0});
    dis[s] = 0;

    while (!q.empty()) {
        Node node = q.top();
        q.pop();
        int u = node.v;
        if (u == t) {
            break;
        }
        if (vis[u]) {
            continue;
        }
        vis[u] = 1;
        for (int i = 0;i < adj[u].size();++i) {
            Edge e = adj[u][i];
            int ndis = dis[u] + e.w;
            if (ndis < dis[e.v]) {
                dis[e.v] = ndis;
                path[e.v] = u;
                q.push({e.v, ndis});
            }
        }
    }

}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> n >> m >> s >> t;

    for (int i = 0; i < m; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        adj[u].push_back({u, v, w});
        adj[v].push_back({v, u, w});
    }

    dijkstra();

    if (dis[t] == 0x3f3f3f3f) {
        cout << "can't arrive" << endl;
        return 0;
    }
    cout << dis[t] << endl;

    vector<int> ans;

    while (t ) {
        ans.push_back(t);
        t = path[t];
    }

    for (int i = ans.size() - 1; i >= 0; i--) {
        cout << ans[i] << " ";
    }



    return 0;
}