// O(MlogN)
// d[nod] = lungimea drumului minim de la Sursa la nod
// prev[nod] = nodul dinaintea lui nod pe drumul minim S-...-prev[nod]-nod-...F
#include <fstream>
#include <vector>
#include <queue>
#define Nmax 50009
#define oo 2000000000
using namespace std;
ifstream f("dijkstra.in");
ofstream g("dijkstra.out");

int N,M,S,F,d[Nmax],prev[Nmax];
struct muchie{int y,c;};
vector < muchie > Graph[Nmax];

struct cmp
{
    bool operator()(int x,int y)
    {
        return d[x]>d[y];
    };
};
priority_queue < int  , vector < int > , cmp > pq;

void ReadInput(),Dijkstra(int S),Rebuild(int nod);

int main()
{
    ReadInput();
    Dijkstra(S);
    g<<"Drumul de la "<<S<< " la "<<F<<" are lungimea "<<d[F]<<" si este:\n";
    Rebuild(F);
    g<<'\n';
    f.close();g.close();
    return 0;
}

void Dijkstra(int S)
{
    for(int i=1;i<=N;++i)d[i]=oo,prev[i]=oo;
    d[S]=prev[S]=0;
    pq.push(S);
    for( ; !pq.empty(); pq.pop() )
    {
        int nod=pq.top();
        for(vector<muchie>::iterator it=Graph[nod].begin() ; it!=Graph[nod].end() ; ++it)
            if(d[nod]+it->c < d[it->y])
            {
                d[it->y]=d[nod]+it->c;
                prev[it->y]=nod;
                pq.push(it->y);
            }
    }
    for (int i=1; i<=N; ++i)
        if (d[i]==oo)d[i]=0,prev[i]=0;
}

void Rebuild(int nod)
{
    if(nod==S){ g<<S<<' '; return; }
    Rebuild(prev[nod]);
    g<<nod<<' ';
}

void ReadInput()
{
    f>>N>>M>>S>>F;
    for(int i=1;i<=M;++i)
    {
        int x,y,c; muchie aux;
        f>>x>>y>>c;
        aux.y=y,aux.c=c;
         Graph[x].push_back(aux);
    }
}