#include <iostream>
#include <vector>
using namespace std;

const int maxn = 100005;
vector<int> graph[maxn];

int main() {
    int num_of_vertices; // n
    cin >> num_of_vertices;

    int num_of_edges; // m
    cin >> num_of_edges;

    for(int i = 0; i < num_of_edges; i++) {
        int a, b;
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }

    for(int i = 0; i <= num_of_vertices; i++) {
        cout << i << " --> ";
        for(int j = 0; j < (int) graph[i].size(); j++) {
            cout << graph[i][j] << " ";
        }
        cout << endl;
    }




    return 0;
}