#include <iostream>
#include <vector>
#include <queue>

using namespace std;

void bfs(int r, vector<bool>& used, vector<vector<int>>& g, vector<int>& way) {
    queue<int> q;
    q.push(r);
    used[r] = true;
    while (!q.empty()) {
        int v = q.front();
        q.pop();
        way.push_back(v);
        for (int i = 0; i < g[v].size(); ++i) {
            int to = g[v][i];
            if (used[to] == false) {
                used[to] = true;
                q.push(to);
            }
        }
    }
}
int main() {
    int n, m, r;
    cin >> n >> m >> r;
    vector<vector<int>> g(n);
    vector<bool> used(n, false);
    vector<int> way;
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        --a, --b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    bfs(r - 1, used, g, way);
    cout << way.size() << endl;
    for (auto x : way) cout << x + 1 << " ";
}