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: Time Limit Exceeded)

from collections import defaultdict
D = defaultdict(set)
N, M = map(int,input().split())

for _ in range(M):
  a, b = map(int,input().split())
  D[a-1].add(b-1)
  D[b-1].add(a-1)

Q = []
ans = 0
S = set()
for i in range(N):
  if i in S:continue
  vstd = set()
  Q.append(i)
  while Q:
    a = Q.pop()
    S.add(a)
    vstd.add(a)
    for j in D[a]:
      if not j in vstd:
        Q.append(j)
  ans = max(ans,len(vstd))
print (ans)