import java.io.*;
import java.util.*;

public class TobiRandomSeparationTranscribed {
    public static void main(String[] args) throws IOException {
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))) {
            new TobiRandomSeparationTranscribed().run(new Scanner(reader));
        }
    }

    public void run(Scanner scanner) throws IOException {
        Random rng = new Random(System.currentTimeMillis());

        int n = scanner.nextInt();
        int m = scanner.nextInt();
        int k = scanner.nextInt();

        List<List<Integer>> adj = new ArrayList<>(n);
        int[] deg = new int[n];
        for (int i = 0; i < n; i++) {
            adj.add(new ArrayList<>());
        }

        for (int i = 0; i < m; i++) {
            int u = scanner.nextInt() - 1;
            int v = scanner.nextInt() - 1;
            adj.get(u).add(v);
            adj.get(v).add(u);
            deg[u]++;
            deg[v]++;
        }

        double error = 0.0001;
        int samples = Math.min(3000, (int) (Math.log(error) / Math.log(1 - Math.pow(4, -k))));
        for (int z = 0; z < samples; z++) {
            boolean[] green = new boolean[n];
            for (int i = 0; i < n; i++) {
                if (deg[i] <= k) {
                    green[i] = rng.nextInt(2) == 1;
                }
            }
            boolean[] vis = new boolean[n];
            List<List<Integer>> components = new ArrayList<>();
            for (int i = 0; i < n; i++) {
                if (green[i] && !vis[i]) {
                    List<Integer> component = new ArrayList<>();
                    component.add(i);
                    vis[i] = true;
                    for (int j = 0; j < component.size(); j++) {
                        for (int v : adj.get(component.get(j))) {
                            if (green[v] && !vis[v]) {
                                component.add(v);
                                vis[v] = true;
                            }
                        }
                    }
                    components.add(component);
                }
            }
            int[] edges = new int[components.size()];
            for (int i = 0; i < components.size(); i++) {
                for (int u : components.get(i)) {
                    for (int v : adj.get(u)) {
                        edges[i] += (!green[v] || u < v) ? 1 : 0;
                    }
                }
            }

            boolean[][] dp = new boolean[components.size() + 1][k + 1];
            dp[0][0] = true;
            for (int i = 0; i < components.size(); i++) {
                for (int j = 0; j <= k; j++) {
                    dp[i + 1][j] |= dp[i][j];
                    if (j + edges[i] <= k) {
                        dp[i + 1][j + edges[i]] |= dp[i][j];
                    }
                }
            }
            if (!dp[components.size()][k]) continue;
            List<Integer> ans = new ArrayList<>();
            for (int i = components.size(), j = k; i > 0 && j > 0; i--) {
                if (dp[i][j] && !dp[i - 1][j]) {
                    ans.addAll(components.get(i - 1));
                    j -= edges[i - 1];
                }
            }
            System.out.println(ans.size());
            for (int i : ans) {
                System.out.println(i + 1);
            }
            return;
        }
        System.out.println("impossible");
    }
}