#include <bits/stdc++.h>

#define el '\n'
#define Beevo ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

typedef long long ll;
typedef long double ld;

using namespace std;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

const int N = 1e5 + 5, INF = 1e9;

vector<pair<int, int>> g[N];
int n, m, dist[N][2], mn[N][2], preMn[N][2];

void pre() {
    for (int i = 1; i <= n; i++) {
        for (int j = 0; j < 2; j++) {
            mn[i][j] = INF;
            dist[i][j] = INF;
        }
    }
}

void dijMin(int u, int st) {
    priority_queue<pair<pair<int, int>, int>> pq;

    dist[u][st] = 0;
    preMn[u][st] = 0;
    pq.push({{0, -INF}, u});

    int c, curMn;
    while (pq.size()) {
        tie(c, curMn) = pq.top().first;

        u = pq.top().second;

        c *= -1, curMn *= -1;

        pq.pop();

        if (dist[u][st] != c || mn[u][st] != curMn)
            continue;

        for (auto &v: g[u]) {
            if (c + 1 < dist[v.first][st] || c + 1 == dist[v.first][st] && min(curMn, v.second) < mn[v.first][st]) {
                dist[v.first][st] = c + 1, mn[v.first][st] = min(curMn, v.second), preMn[v.first][st] = u;

                pq.push({{-dist[v.first][st], -mn[v.first][st]}, v.first});
            }
        }
    }
}

void testCase() {
    cin >> n >> m;

    int u, v, c;
    vector<pair<pair<int, int>, int>> edges;
    for (int i = 0; i < m; i++) {
        cin >> u >> v >> c;

        g[u].emplace_back(v, c);
        g[v].emplace_back(u, c);

        edges.push_back({{u, v}, c});
    }

    pre();

    dijMin(1, 0), dijMin(n, 1);

    int sol = -1;
    pair<int, int> e;
    for (auto &i: edges) {
        u = i.first.first, v = i.first.second, c = i.second;

        if (dist[u][0] + dist[v][1] + 1 == dist[n][0]) {
            int cur = i.second - min({mn[u][0], mn[v][1], i.second});

            if (cur > sol)
                sol = cur, e = {u, v};
        }

        swap(u, v);

        if (dist[u][0] + dist[v][1] + 1 == dist[n][0]) {
            int cur = i.second - min({mn[u][0], mn[v][1], i.second});

            if (cur > sol)
                sol = cur, e = {u, v};
        }
    }

    u = e.first, v = e.second;

    vector<int> p;
    while (v)
        p.push_back(v), v = preMn[v][1];

    reverse(p.begin(), p.end());

    while (u)
        p.push_back(u), u = preMn[u][0];

    reverse(p.begin(), p.end());

    cout << p.size() - 1 << el;

    for (auto &i: p)
        cout << i << ' ';
}

signed main() {
    Beevo

    int t = 1;
//    cin >> t;

    while (t--)
        testCase();
}