CENTRE28 || DIJKSTRA

//Nguyen Huu Hoang Minh
#include <bits/stdc++.h>
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define reset(x) memset(x, 0,sizeof(x))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define N 30005
#define remain(x) if (x > MOD) x -= MOD
#define ii pair<int, int>
#define vi vector<int>
#define vii vector< ii >
#define bit(x, i) (((x) >> (i)) & 1)
#define Task "test"
#define int long long

using namespace std;

typedef long double ld;

int n,m;
vector<ii> a[N];
int ds[N], dt[N];
int fs[N], ft[N];

void readfile()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    if (fopen(Task".inp","r"))
    {
        freopen(Task".inp","r",stdin);
        //freopen(Task".out","w",stdout);
    }
    cin >> n >> m;
    for(int i=1; i<=m; i++)
    {
        int u,v,z;
        cin >> u >> v >> z;
        a[u].pb(ii(v,z));
        a[v].pb(ii(u,z));
    }
}

void dijkstra()
{
    priority_queue<ii, vii, greater<ii>> q;
    for(int i=1; i<=n; i++) ds[i] = dt[i] = 99999999999;
    ds[1] = 0;
    fs[1] = 1;
    q.push(ii(0,1));
    while (q.size())
    {
        int u = q.top().se;
        int du = q.top().fi;
        q.pop();
        if (du != ds[u]) continue;
        for(int i=0; i<a[u].size(); i++)
        {
            int v = a[u][i].fi;
            int uv = a[u][i].se;
            if (ds[v] > ds[u] + uv)
            {
                ds[v] = ds[u] + uv;
                fs[v] = fs[u];
                q.push(ii(ds[v],v));
            }
            else if (ds[v] == ds[u] + uv) fs[v] += fs[u];
        }
    }
    dt[n] = 0;
    ft[n] = 1;
    q.push(ii(0,n));
    while (q.size())
    {
        int u = q.top().se;
        int du = q.top().fi;
        q.pop();
        if (du != dt[u]) continue;
        for(int i=0; i<a[u].size(); i++)
        {
            int v = a[u][i].fi;
            int uv = a[u][i].se;
            if (dt[v] > dt[u] + uv)
            {
                dt[v] = dt[u] + uv;
                ft[v] = ft[u];
                q.push(ii(dt[v],v));
            }
            else if (dt[v] == dt[u] + uv) ft[v] += ft[u];
        }
    }
}

void proc()
{
    dijkstra();
    int D = ds[n];
    vector<int> res;
    for(int i=2; i<n; i++)
    {
        if (ds[i] + dt[i] > D || fs[i]*ft[i] < fs[n]) res.pb(i);
    }
    cout << res.size() << '\n';
    for(auto u : res) cout << u << '\n';
}

signed main()
{
    readfile();
    proc();
    return 0;
}