Problem:
Score : 400 points

Problem Statement

There are N persons called Person 1 through Person N.

You are given M facts that "Person A_i and Person B_i are friends." The same fact may be given multiple times.

If X and Y are friends, and Y and Z are friends, then X and Z are also friends. There is no friendship that cannot be derived from the M given facts.

Takahashi the evil wants to divide the N persons into some number of groups so that every person has no friend in his/her group.

At least how many groups does he need to make?

Constraints

2 \leq N \leq 2\times 10^5

0 \leq M \leq 2\times 10^5

1\leq A_i,B_i\leq N

A_i \neq B_i

Input

Input is given from Standard Input in the following format:

N M
A_1 B_1
\vdots
A_M B_M

Output

Print the answer.

Sample Input 1

5 3
1 2
3 4
5 1

Sample Output 1

3

Dividing them into three groups such as \{1,3\}, \{2,4\}, and \{5\} achieves the goal.

Sample Input 2

4 10
1 2
2 1
1 2
2 1
1 2
1 3
1 4
2 3
2 4
3 4

Sample Output 2

4

Sample Input 3

10 4
3 1
4 1
5 9
2 6

Sample Output 3

3

Solution in C# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;
using static System.Console;
using static System.Math;
using System.Numerics;
using System.Collections.Generic;
using System.Linq;


namespace AtCoder
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var s = myRead.readIntArray();
            int[] num = new int[s[0]];
            num = num.Select(x => 1).ToArray();
            int[] parent = new int[s[0]];
            for (int i = 0; i < s[0]; i++)
            {
                parent[i] = i;
            }
            int max = 0;
            for (int i = 0; i < s[1]; i++)
            {
                var t = myRead.readIntArray().Select(x => x - 1).ToArray();
                int p0 = parent[t[0]] == t[0] ? t[0] : parent[t[0]];
                int p1 = parent[t[1]] == t[1] ? t[1] : parent[t[1]];
                if (p0 != p1)
                {
                    int min = p0 > p1 ? p1 : p0;
                    int m = p0 > p1 ? p0 : p1;
                    num[min] += num[m];
                    parent[m] = min;
                    max = num[min] > max ? num[min] : max;
                }
            }
            WriteLine(max);
        }
    }
    public static class myRead
    {
        public static int readInt() { return int.Parse(ReadLine()); }
        public static long readLong() { return long.Parse(ReadLine()); }
        public static string readStr() { return ReadLine(); }
        public static int[] readIntArray() { return ReadLine().Split(' ').Select(int.Parse).ToArray(); }
        public static long[] readLongArray() { return ReadLine().Split(' ').Select(long.Parse).ToArray(); }
        public static string[] readStrArray() { return ReadLine().Split(' '); }
    }


    public static class MyMath
    {
        public static long Factorical(long n)
        { return n <= 1 ? 1L : n * Factorical(n - 1); }
        public static long Permutation(long n, long m)
        { return m == 0 ? 1L : (m == n) ? Permutation(n, m - 1) : n * Permutation(n - 1, m - 1); }
        public static long Combination(long n, long m)
        { return n - m > m ? Permutation(n, m) / Factorical(m) : Permutation(n, n - m) / Factorical(n - m); }
        public static long Gcd(long n, long m)
        { return n % m == 0 ? m : Gcd(m, n % m); }
        public static long Lcm(long n, long m)
        { return n * m / Gcd(n, m); }
        public static long Pow(long n, long m)
        { return m == 0 ? 1L : m == 1 ? n : n * Pow(n, m - 1); }
    }


}