//dijktra
#include<iostream>
#include<fstream>
using namespace std;
typedef unsigned int ui;
ifstream fi("input.inp");
ofstream fo("output.out");

ui sum=0;

void nhap(ui **&a,ui *&length,ui *&p,bool *&s,ui &n,ui &m,ui &dau,ui &cuoi){
    fi>>n>>m>>dau>>cuoi;dau--;cuoi--;
    ui i,j,u,v;
    a=new ui*[n];length=new ui[n];p=new ui[n];s=new bool[n];
    for(i=0;i<n;i++) a[i]=new ui[n];
    for(i=0;i<n;i++){
        for(j=0;j<n;j++) a[i][j]=0;
    }
//  khoi tao matran va mang
    for(i=0;i<m;i++){
        fi>>u>>v;u--;v--;
        fi>>a[u][v];
 //       a[u][v]=1;a[v][u]=1;
        sum=sum+a[u][v];
    }
    sum++;
    for(i=0;i<n;i++){
        length[i]=sum;
        p[i]=dau;
        s[i]=true;
        for(j=0;j<n;j++) if(i!=j&&a[i][j]==0) a[i][j]=sum;
    }
/*  for(i=0;i<n;i++){
        for(j=0;j<n;j++) cout<<a[i][j]<<"\t";
        cout<<endl;
    }*/
    length[dau]=0;
}

void dijika(ui **a,ui *length,ui *p,bool *s,ui n,ui dau,ui cuoi){
    ui i,j;
    while(s[cuoi]){
        for(i=0;i<n;i++) if(s[i]&&length[i]<sum) break;
        if(i>=n) break;
        for(j=0;j<n;j++) if(s[j]&&length[i]>length[j]) i=j;
        s[i]=false;
        for(j=0;j<n;j++) if(s[j]&&length[j]>a[i][j]+length[i]){
            length[j]=a[i][j]+length[i];
            p[j]=i;
        }
    }
}

void xuat(ui i,ui dau,ui *p){
    if(i==dau){
        fo<<i+1<<"\t";
        return;
    }
    xuat(p[i],dau,p);
    fo<<i+1<<"\t";
}

int main(){
    ui **a,*length,*p,n,m,dau,cuoi;
    bool *s;
    nhap(a,length,p,s,n,m,dau,cuoi);
    dijika(a,length,p,s,n,dau,cuoi);
    if(length[cuoi]>0&&length[cuoi]<sum){
        fo<<length[cuoi]<<endl;
        xuat(cuoi,dau,p);
    }
    else cout<<"khong tim duoc duong\n";
    fi.close();fo.close();
    delete []s;delete []p;delete []length;
    for(m=0;m<n;m++) delete []a[m];
    delete []a;
    return 0;
}