#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <sstream>
#include <string>

#define repd(i,a,b) for (int i=(a);i<(b);i++)
#define rep(i,n) repd(i,0,n)
#define var auto
#define mod 1000000007
#define inf 2147483647
typedef long long ll;

using namespace std;

int inputValue(){
    int a;
    cin >> a;
    return a;
}

template <typename T>
void output(T a, int precision) {
    if(precision > 0){
        cout << fixed << setprecision(precision)  << a << "\n";
    }
    else{
        cout << a << "\n";
    }
}

// end of template

int main() {
    // source code
    int N = inputValue(); // station
    int M = inputValue(); // line
    int S = inputValue(); // start
    int G = inputValue(); // goal
    
    vector<vector<ll>> E(N, vector<ll>(N, inf));
    vector<vector<int>> C(N, vector<int>(N, 0));
    
    rep(i, N){
        E[i][i] = 0;
    }
    rep(i, M){
        int a, b, c;
        cin >> a >> b >> c;
        E[a][b] = c;
        E[b][a] = c;
        C[a][b] = c;
        C[b][a] = c;
    }
    
    rep(k, N){
        rep(i, N){
            rep(j, N){
                E[i][j] = min(E[i][j], E[i][k] + E[k][j]);
            }
        }
    }
    
    output(S, 0);
    while (S != G) {
        rep(i, N){
            if (C[S][i] && C[S][i] + E[i][G] == E[S][G]) {
                output(i, 0);
                S = i;
                break;
            }
        }
    }
    // output(G, 0);
    
    
    return 0;
}