DFS

/*    Never let anyone dull your sparkle...    */
#include <bits/stdc++.h>
using namespace std;

// type definition
#define int long long
using i64 = int64_t;
typedef pair<int, int> ii;
// constants
constexpr int N = 2e6 + 2;
constexpr int INF = 0x3f3f3f3f;
constexpr int MOD = 1e9 + 7;
constexpr float PI = 3.14;
// possible moves
constexpr int dx[8] = {1, 1, -1, -1, 0, 0, 1, -1};
constexpr int dy[8] = {1, 0, -1, 0, 1, -1, -1, 1};
// shortcuts
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fi first
#define se second
#define endl '\n'
#define sz(x) i64(x.size())
#define all(x) begin(x), end(x)
#define rall(x) begin(x), end(x), greater<int>()
// loop definition
#define FOR(i, n, m) for (int i = n; i <= m; ++i)
#define FORD(i, n, m) for (int i = n; i >= m; --i)

int n, m, s, t;
vector<int> g[N];
bool visited[N];
int parent[N];
void DFS(int u) {
    visited[u] = true;

    for (auto v : g[u]) {
        if (!visited[v]) {
            parent[v] = u;
            DFS(v);
        }
    }
}
void print_path() {
    if (!visited[t]) {
        cout << "No path!";
    }
    else {
        vector<int> path;
        while (t != s) {
            path.pb(t);
            t = parent[t];
        }
        path.pb(s);
        reverse(all(path));
        for (auto i : path) cout << i << ' ';
    }
}
int32_t main(void) {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    //freopen("main.INP", "r", stdin);
    //freopen("main.OUT", "w", stdout);

    cin >> n >> m >> s >> t;
    while (m--) {
        int x, y;
        cin >> x >> y;
        g[x].pb(y);
        g[y].pb(x);
    }

    DFS(s);
    print_path();
    return 0;
}