#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx")
// #pragma comment(linker, "/stack:200000000"]

#include <iostream>
#include <vector>
#include <cmath>
#include <algorithm>
#include <unordered_set>
#include <unordered_map>
#include <set>
#include <map>
#include <queue>
#include <deque>
#include <bitset>
#include <stack>
#include <random>
#include <fstream>
#include <sstream>
#include <chrono>

#define fi first
#define se second
#define pb push_back
#define ll long long
#define ld long double
#define hm unordered_map
#define pii pair<int, int>
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define cinv(v) for (auto& x: v) cin >> x
#define fr(i, n) for (int i = 0; i < n; ++i)
#define fl(i, l, n) for (int i = l; i < n; ++i)

// #define int ll

template <typename T1, typename T2> inline bool chkmin(T1 &x, const T2 &y) {if (x > y) {x = y; return 1;} return 0;}
template <typename T1, typename T2> inline bool chkmax(T1 &x, const T2 &y) {if (x < y) {x = y; return 1;} return 0;}

using namespace std;

#ifdef __LOCAL
	#define dbg(x) cerr << #x << " : " << x << '\n'
	const int maxn = 20;
#else
	#define dbg(x)
	const int maxn = 3e5 + 20;
#endif

//tg: @galebickosikasa

ostream& operator << (ostream& out, vector<int>& v) {
	for (auto& x: v) out << x << ' ';
	return out;
}

ostream& operator << (ostream& out, pii& v) {
	out << v.fi << ", " << v.se;
	return out;
}

ostream& operator << (ostream& out, vector<pii>& v) {
	for (auto& x: v) out << x << "  ";
	return out;
}

istream& operator >> (istream& in, pii& a) {
	in >> a.fi >> a.se;
	return in;
}

const ll inf = (ll) 2e9;
const ld pi = asin (1) * 2;
const ld eps = 1e-8;
const ll mod = (ll)1e9 + 7;
const ll ns = 97;

mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());

struct qs {
	int l, r, i;

	bool operator < (const qs& other) const {
		if (r != other.r) return r < other.r;
		return l < other.l;
	}
};

vector<int> g[maxn];
int m;

inline int check (vector<qs>& goo, int x) {
	fr (i, m) g[i].clear ();
	set <int> s;
	fr (i, m) s.insert (i);
	for (auto& r: goo) {
		auto it = s.lower_bound (r.l);
		if (it != s.end () && *it <= r.r) {
			g[*it].pb (r.i);
			if (sz (g[*it]) >= x) {
				s.erase (it);
			}
		} else return 0;
	}
	return 1;
}

inline int BS (vector<qs>& goo) {
	int l = 0, r = (int)3e5;
	while (r - l > 1) {
		int m = (r + l) / 2;
		if (check (goo, m)) r = m;
		else l = m;
	}
	check (goo, r);
	return r;
}

signed main () {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	int n;
	cin >> n >> m;
	vector<qs> goo (n);
	for (auto& x: goo) cin >> x.l >> x.r;
	for (auto& x: goo) --x.l, --x.r;
	fr (i, n) goo[i].i = i;
	sort (all (goo));
	int mx = BS (goo);
	check (goo, mx);
	cout << mx << '\n';
	fr (i, m) {
		cout << sz (g[i]) << ' ';
		for (auto& x: g[i]) cout << x + 1 << ' ';
		cout << '\n';
	}






}