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 Python (3.8.2) (judge verdict: Wrong Answer)

import collections as col
from collections import defaultdict as dd

d=dd(list)

N,M=map(int, input().split())
p=[-1]*N
cnt=[0]*N

for _ in range(M):
    i,j=map(int, input().split())
    if i>j:
        i,j=j,i
    d[i].append(j)


for i in d:
    for j in d[i]:
        if p[j-1]!=-1:
            continue
        if p[i-1]==-1:
            p[j-1]=i
            cnt[i]+=1
        else:
            p[j-1]=p[i-1]
            cnt[p[i-1]]+=1

cnt.sort(reverse=True)

print(cnt[0]+1)