import java.util.Scanner;

public class Graph {

    static boolean adj[][];
    static boolean visitado[];
    static boolean cor[];
    static int n;

    static void dfs(int v) {
        visitado[v] = true;
        for (int i = 1; i <= n; i++)
            if (adj[v][i] && !visitado[i]) {
                dfs(i);
            }
    }

    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextInt()) {

            n = in.nextInt();
            if (n == 0) {
                break;
            }
            adj = new boolean[n + 1][n + 1];
            visitado = new boolean[n + 1];
            int edges = in.nextInt();
            for (int i = 0; i < edges; i++) {
                int a = in.nextInt();
                int b = in.nextInt();
                adj[a][b] = adj[b][a] = true;
            }

            dfs(1);
            System.out.println();
        }
    }
}