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: Accepted)

n, m = map(int, input().split())
# print(n,m)

V = [set() for _ in range(n)]
for a, b in [[*map(lambda x: int(x)-1, input().split())] for _ in range(m)]:
    V[a].add(b)
    V[b].add(a)
# print(V)

from collections import deque
G = [-1] * n
for s in range(n):
    dq = deque([s])
    while dq:
        p = dq.popleft()
        if G[p] >= 0: continue
        G[p] = s
        for c in V[p]:
            if G[c] >= 0: continue
            dq.append(c)
# print(G)

C = dict()
for g in G:
    if not g in C: C[g] = 0
    C[g] += 1
# print(C)

print(max(C.values()))