LEXIPATH

#include <bits/stdc++.h>
using namespace std;

const int INF = 1e9 + 7;
const int N = 105;

int n, m, s, t;
vector<int> graph[N];

int visited[N];
int parent[N];

void DFS(int u) {
    visited[u] = true;

    for (int v : graph[u]) {
        if (!visited[v]) {
            parent[v] = u;
            visited[v] = true;
            DFS(v);
        }
    }
}

vector<int> ans;
void Trace(int s, int t) {
    ans.push_back(t);

    int u = parent[t];
    if (s == u) {
        ans.push_back(s);
        return;
    }

    Trace(s, u);
}

void solve() {
    cin >> n >> m >> s >> t;
    for (int i = 1; i <= m; ++i) {
        int u, v; cin >> u >> v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }

    for (int i = 1; i <= n; ++i)
        sort(graph[i].begin(), graph[i].end());
    iota(parent + 1, parent + n + 1, 1);

    DFS(s);
    Trace(s, t);

    reverse(ans.begin(), ans.end());
    for (int u : ans)
        cout << u << ' ';


    return;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    solve();

    return 0;
}