#include <bits/stdc++.h>

using namespace std;

int pontok[102];
vector<vector<int> > kiir;

int main()
{
    int n, m;
    cin >> n >> m;
    kiir.resize(m+1);
    int nagy = 0;
    vector<int> jok;
    for (int j = 1; j<=m; j++) {
        int x, y;
        cin >> x >> y;
        pontok[x]++;
        pontok[y]--;
        nagy = 0;
        for (int i = 1; i<=n; i++) {
            nagy = max(nagy,pontok[i]);
        }
        for (int i = 1; i<=n; i++) {
            if (nagy == pontok[i]) {
                jok.push_back(i);
            }
        }
        kiir[j].push_back(jok.size());
        for (int x : jok) {
            kiir[j].push_back(x);
        }
        jok.clear();
    }
    for (int j = 1; j<=m; j++) {
        if (j > 1) {
            cout << endl;
        }
        cout << kiir[j][0];
        for (int i = 1; i<kiir[j].size(); i++) {
            cout << " " << kiir[j][i];
        }
    }
    return 0;
}