Berland has managed to repel the flatlanders' attack and is now starting the counter attack.

Flatland has n cities, numbered from 1 to n, and some pairs of them are connected by bidirectional roads. The Flatlandian maps show roads between cities if and only if there is in fact no road between this pair of cities (we do not know whether is it a clever spy-proof strategy or just saving ink). In other words, if two cities are connected by a road on a flatland map, then there is in fact no road between them. The opposite situation is also true: if two cities are not connected by a road on a flatland map, then in fact, there is a road between them.

The berlanders got hold of a flatland map. Now Vasya the Corporal is commissioned by General Touristov to find all such groups of flatland cities, that in each group of cities you can get from any city to any other one, moving along the actual roads. Also the cities from different groups are unreachable from each other, moving along the actual roads. Indeed, destroying such groups one by one is much easier than surrounding all Flatland at once!

Help the corporal complete this task and finally become a sergeant! Don't forget that a flatland map shows a road between cities if and only if there is in fact no road between them. 

Input

The first line contains two space-separated integers n and m (1 ≤ n ≤ 5·105, 0 ≤ m ≤ 106) — the number of cities and the number of roads marked on the flatland map, correspondingly.

Next m lines contain descriptions of the cities on the map. The i-th line contains two integers ai and bi (1 ≤ ai, bi ≤ n, ai ≠ bi) — the numbers of cities that are connected by the i-th road on the flatland map.

It is guaranteed that each pair of cities occurs in the input no more than once.

Output

On the first line print number k — the number of groups of cities in Flatland, such that in each group you can get from any city to any other one by flatland roads. At the same time, the cities from different groups should be unreachable by flatland roads.

On each of the following k lines first print ti (1 ≤ ti ≤ n) — the number of vertexes in the i-th group. Then print space-separated numbers of cities in the i-th group.

The order of printing groups and the order of printing numbers in the groups does not matter. The total sum ti for all k groups must equal n.

Examples

Input

4 4
1 2
1 3
4 2
4 3


Output

2
2 1 4 
2 2 3 


Input

3 1
1 2


Output

1
3 1 2 3 

Note

In the first sample there are roads only between pairs of cities 1-4 and 2-3.

In the second sample there is no road between cities 1 and 2, but still you can get from one city to the other one through city number 3.
// package cf190;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.*;
import java.util.function.IntConsumer;
import java.util.stream.Collectors;

public class CFE {
    private static final long MOD = 1_000_000_007;
    private static final String INPUT = "4 4\n" +
            "1 2\n" +
            "1 3\n" +
            "4 2\n" +
            "4 3\n";

    private PrintWriter out;
    private FastScanner sc;

    public static void main(String[] args) {
        new CFE().run();
    }

    public void run() {
        sc = new FastScanner(oj ? System.in : new ByteArrayInputStream(INPUT.getBytes()));
        out = new PrintWriter(System.out);

        long s = System.currentTimeMillis();
        try {
            solve();
        } catch (ExitException ignored) {
        }
        out.flush();
        tr(System.currentTimeMillis() - s + "ms");
    }

    static class IntArray {
        int[] array;
        int size;

        IntArray() {
            this(20);
        }

        IntArray(int capacity) {
            this.array = new int[capacity];
        }

        void add(int n) {
            ensureCapacity(size + 1);
            array[size++] = n;
        }

        void sort() {
            shuffle();
            Arrays.sort(array, 0, size);
        }

        void shuffle() {
            for (int i = 0; i < size; i++) {
                int r = i + (int) (Math.random() * (size - i));
                { int tmp = array[i]; array[i] = array[r]; array[r] = tmp; }
            }
        }

        boolean contains(int n) {
            int lo = -1;
            int hi = size;
            while (hi-lo > 1) {
                int med = (hi+lo)>>1;
                int mValue = array[med];
                if (mValue == n) return true;
                else if (mValue < n) lo = med;
                else hi = med;
            }
            return false;
        }

        private void ensureCapacity(int cap) {
            if (cap > array.length) grow(cap);
        }

        private void grow(int cap) {
            int oldCapacity = array.length;
            int newCapacity = oldCapacity + (oldCapacity >> 1);
            array = Arrays.copyOf(array, newCapacity);
        }
    }

    int n;
    IntArray cities;
    IntArray[] ways;
    public void solve() {
        n = sc.nextInt();
        int m = sc.nextInt();
        cities = new IntArray(n);
        for (int i = 1; i <= n; i++) cities.add(i);

        ways = new IntArray[n+1];
        for (int i = 1; i <= n; i++) ways[i] = new IntArray();

        for (int i = 0; i < m; i++) {
            int a = sc.nextInt();
            int b = sc.nextInt();
            ways[a].add(b);
            ways[b].add(a);
        }
        for (int i = 1; i <= n; i++) ways[i].sort();

        List<IntArray> ans = new ArrayList<>();
        for (int i = 1; i <= n; i++) {
            if (cities.contains(i)) {
                IntArray cans = new IntArray(10);
                dfs(i, cans);
                ans.add(cans);
            }
        }

        out.println(ans.size());
        for (IntArray an : ans) {
            out.print(an.size + " ");
            int[] array = an.array;
            for (int i = 0; i < an.size; i++) {
                out.print(array[i] + " ");
            }
            out.println();
        }
    }

    private void dfs(int ccity, IntArray cans) {
        cans.add(ccity);
        IntArray newCities = new IntArray(cities.size);
        IntArray edges = ways[ccity];
        IntArray nexts = new IntArray();
        int ie = 0;
        int nEdge = ie < edges.size ? edges.array[ie++] : Integer.MAX_VALUE;
        int[] array = cities.array;
        for (int i = 0, length = cities.size; i < length; i++) {
            int city = array[i];
            if (city == ccity) continue;
            while (city > nEdge) nEdge = ie < edges.size ? edges.array[ie++] : Integer.MAX_VALUE;
            if (city < nEdge) nexts.add(city);
            else newCities.add(city);
        }

        cities = newCities;
        for (int i = 0; i < nexts.size; i++) {
            dfs(nexts.array[i], cans);
        }
    }

    //********************************************************************************************
    //********************************************************************************************
    //********************************************************************************************

    private void times(int n, IntConsumer consumer) {
        for (int i = 0; i < n; i++) {
            try {
                consumer.accept(i);
            } catch (ExitException ignored) {
            }
        }
    }

    private static class ExitException extends RuntimeException {
    }

    private void answer(Object ans) {
        out.println(ans);
        throw new ExitException();
    }

    private static int lowerBound(long[] arr, long key) {
        int lo = 0;
        int hi = arr.length - 1;
        while (lo < hi) {
            int mid = (lo + hi) / 2;
            if (key <= arr[mid]) {
                hi = mid - 1;
            } else {
                lo = mid + 1;
            }
        }
        return arr[lo] < key ? lo + 1 : lo;
    }

    private static int upperBound(long[] arr, long key) {
        int lo = 0;
        int hi = arr.length - 1;
        while (lo < hi) {
            int mid = (lo + hi) / 2;
            if (key >= arr[mid]) {
                lo = mid + 1;
            } else {
                hi = mid;
            }
        }
        return arr[lo] <= key ? lo + 1 : lo;
    }

    private static int ceil(double d) {
        int ret = (int) d;
        return ret == d ? ret : ret + 1;
    }

    private static int round(double d) {
        return (int) (d + 0.5);
    }

    private static int gcd(int a, int b) {
        BigInteger b1 = BigInteger.valueOf(a);
        BigInteger b2 = BigInteger.valueOf(b);
        BigInteger gcd = b1.gcd(b2);
        return gcd.intValue();
    }

    private static long gcd(long a, long b) {
        BigInteger b1 = BigInteger.valueOf(a);
        BigInteger b2 = BigInteger.valueOf(b);
        BigInteger gcd = b1.gcd(b2);
        return gcd.longValue();
    }

    private int[] readIntArray(int n) {
        int[] res = new int[n];
        for (int i = 0; i < n; i++) {
            res[i] = sc.nextInt();
        }
        return res;
    }

    private long[] readLongArray(int n) {
        long[] res = new long[n];
        for (int i = 0; i < n; i++) {
            res[i] = sc.nextLong();
        }
        return res;
    }

    @SuppressWarnings("unused")
    static class FastScanner {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;

        FastScanner(InputStream stream) {
            this.stream = stream;
        }

        int read() {
            if (numChars == -1)
                throw new InputMismatchException();
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (numChars <= 0) return -1;
            }
            return buf[curChar++];
        }

        boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        boolean isEndline(int c) {
            return c == '\n' || c == '\r' || c == -1;
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public String next() {
            int c = read();
            while (isSpaceChar(c)) c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public String nextLine() {
            int c = read();
            while (isEndline(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isEndline(c));
            return res.toString();
        }

    }

    private boolean oj = System.getProperty("ONLINE_JUDGE") != null;

    private void tr(Object... o) {
        if (!oj) System.out.println(Arrays.deepToString(o));
    }
}