#include <iostream>
#include <fstream>
using namespace std;

ifstream fin("lant1.in");
ofstream fout("lant1.out");

int n , p , q , r , a[105][105];
int x[105], // coada pentru parcurgerea in latime
    v[105], // vector caracteristic care precizeaza daca un varf a fost sau nu vizitat
    t[105]; // vectorul de tati
int sol[205], nsol;

void bfs(int p, int q)
{
    int st, dr;
    st = dr = 1;
    v[p] = 1;
    x[1] = p;
    t[p] = 0;
    while(st <= dr)
    {
        int k = x[st];
        for(int i = 1; i <= n ; ++i)
            if(v[i] == 0 && a[k][i] == 1)
            {
                dr ++;
                v[i] = 1;
                x[dr] = i;
                t[i] = k;
            }
        st ++;
    }
}

void reconstituire(int p)
{
    if(p)
    {
        reconstituire(t[p]);
        sol[ ++nsol ] = p;
    }
}

void afis(int *x , int n)
{
    for(int i = 1; i <= n ;++i)
        fout << x[i] << " ";
    fout << endl;
}

int main()
{
    int i , j;
    fin >> n >> p >> q >> r;
    while(fin >> i >> j)
    {
        a[i][j] = a[j][i] = 1;
    }
    for(int  i = 1 ; i <= n ; ++i)
        t[i] = 0, v[i] = 0;
    bfs(p , r);
    reconstituire(t[r]);
    for(int  i = 1 ; i <= n ; ++i)
        t[i] = 0, v[i] = 0;
    bfs(r , q);
    reconstituire(q);
    fout << nsol << "\n";
    afis(sol, nsol);
    return 0;
}