#include <iostream>
#include <vector>
#include <queue>
#include<stack>
using namespace std;

typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
vector<vii> AdjList;
priority_queue< ii, vector<ii>, greater<ii> > pq;
vi dist;
vi pre;
#define INF 1000000000

void dijkstra(int s){
dist[s] = 0;
pq.push(ii(0, s));

while (!pq.empty()) {
 ii front = pq.top();
 pq.pop();
 int w = front.first;
 int u = front.second;
 if (w > dist[u]){
    continue;
 }
 for (int j = 0; j < AdjList[u].size(); j++) {
    ii v = AdjList[u][j];
    if (dist[u] + v.second < dist[v.first]) {
    dist[v.first] = dist[u] + v.second;
    pq.push(ii(dist[v.first], v.first));
        pre[v.first]=u;
   }
  }
 }
}

int main() {

int A, B, V, E, s, a, b, w;
cin >>A>>B>> V >> E;
AdjList.assign(V, vii());
dist.assign(V, INF);
pre.assign(V, 0);
for (int i = 0; i < E; i++) {
   cin >> a >> b >> w;
   AdjList[a].push_back(ii(b, w));
  }
    dijkstra(A);
    stack<int> path;

  if (dist[B] != INF){
    path.push(B);
    cout << dist[B] << endl;
    int p = pre[B];
    while (p!=A){
        path.push(p);
        p = pre[p];
    }
     path.push(A);
     while (!path.empty()){
         cout << path.top() << " ";
         path.pop();
     }
  }
  else
      cout << "-1";
return 0;
}