#include <cstdio>
#include <queue>
#include <utility>
#include <cstring>
using namespace std;
const int maxn = 2e5 + 10, maxm = 1e6 + 10, inf = 522133279;
int n, m, s, t;
int head[maxn], nxt[maxm], to[maxm], w[maxm], tot = 1;
int dis[maxn << 1], *dis2;
int pre[maxn << 1], *pre2;
bool vis[maxn << 1];
void add(int a, int b, int c) {
	++tot;
	nxt[tot] = head[a];
	to[tot] = b;
	w[tot] = c;
	head[a] = tot;
}
bool upd(int a, int b, int d, priority_queue<pair<int, int> > &q) {
	if (d >= dis[b])return false;
	if (b < n) __(1)__ ;
	q.push( __(2)__ );
	dis[b] = d;
	pre[b] = a;
	return true;
}
void solve() {
	priority_queue<pair<int, int> >q;
	q.push(make_pair(0, s));
	memset(dis, __(3)__ , sizeof(dis));
	memset(pre, -1, sizeof(pre));
	dis2 = dis + n;
	pre2 = pre + n;
	dis[s] = 0;
	while (!q.empty()) {
		int aa = q.top().second;
		q.pop();
		if (vis[aa])continue;
		vis[aa] = true;
		int a = aa % n;
		for (int e = head[a]; e; e = nxt[e]) {
			int b = to[e], c = w[e];
			if (aa < n) {
				if (!upd(a, b, dis[a] + c, q))
					__(4)__
				} else {
				upd(n + a, n + b, dis2[a] + c, q);
			}
		}
	}
}
void out(int a) {
	if (a != s) {
		if (a < n)
			out(pre[a]);
		else
			out( __(5)__ );
	}
	printf("%d%c", a % n + 1, " \n"[a == n + t]);
}
int main() {
	scanf("%d%d%d%d", &n, &m,&s,&t);
	s--, t--;
	for (int i = 0; i < m; i++) {
		int a, b, c;
		scanf("%d%d%d", &a, &b, &c);
		add(a - 1, b - 1, c);
	}
	solve();
	if (dis2[t] == inf)
		puts("-1");
	else {
		printf("%d\n", dis2[t]);
		out(n + t);
	}
	return 0;
}