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

int n, m; int s,t; int a[1010][1010]; vector 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) {
        int v = adj[u][i];
        int ndis = dis[u] + a[u][v];
        if (ndis < dis[v]) {
            dis[v] = ndis;
            path[v] = u;
            q.push({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;
    if (a[u][v] == 0 || w < a[u][v]) {
        if (a[u][v] == 0) {
            adj[u].push_back(v);
            adj[v].push_back(u);
        }
        a[u][v] = w;
        a[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;

}