#include<iostream>
#include <bits/stdc++.h>

#define ll long long
#define IO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
const int N = 2e5 + 5, inf = 2e9;
int n, m;

vector<pair<int, int> > adj[N];
pair<int, int> dis[2][N];
int par[2][N];

void dijkstra(int source, pair<int, int> dis[], int par[]) {
    fill(dis, dis + N, make_pair(inf, inf));
    dis[source] = make_pair(0, inf);

    queue<vector<int>> q;
    q.push({0, inf, source});
    while (!q.empty()) {
        vector<int> temp = q.front();
        q.pop();
        int d = temp[0], mn_edge = temp[1], node = temp[2];
        if (dis[node] != make_pair(d, mn_edge)) continue;

        for (auto child: adj[node]) {
            if (make_pair(d + 1, min(mn_edge, child.second)) < dis[child.first]) {
                par[child.first] = node;
                dis[child.first] = make_pair(d + 1, min(mn_edge, child.second));
                q.push({d + 1, min(mn_edge, child.second), child.first});
            }
        }
    }
}

pair<int, int> calc(vector<int> edge) {

    return {dis[0][edge[0]].first + dis[1][edge[1]].first + 1,
            min(dis[0][edge[0]].second, dis[1][edge[1]].second) - edge[2]};
}

void doWork() {
    cin >> n >> m;
    while (m--) {
        int u, v, w;
        cin >> u >> v >> w;
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }

    dijkstra(1, dis[0], par[0]);
    dijkstra(n, dis[1], par[1]);

    vector<int> mid_edge = {1, adj[1][0].first, adj[1][0].second};

    for (int i = 1; i <= n; i++) {
        for (auto child: adj[i]) {
            if (calc({i, child.first, child.second}) < calc(mid_edge)) {
                mid_edge = {i, child.first, child.second};
            }
        }
    }
    vector<int> ans;
    int x = mid_edge[0], y = mid_edge[1];
    while (par[0][x]) {
        ans.push_back(x);
        x = par[0][x];
    }
    ans.push_back(1);
    reverse(ans.begin(), ans.end());
    while (par[1][y]) {
        ans.push_back(y);
        y = par[1][y];
    }
    ans.push_back(n);
    cout << (int) ans.size() - 1 << "\n";
    for (auto i: ans)cout << i << " ";

}

int main() {
    IO
    int t = 1;
    // cin >> t;
    for (int i = 1; i <= t; i++) {
        //  cout << "Case #" << i << ": ";
        doWork();
    }
}