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 Julia (1.4.0) (judge verdict: Runtime Error)

N,M=parse.(Int,split(readline()))
AB=zeros(Bool,N,N)
for i=1:M
a,b=parse.(Int,split(readline()))
AB[a,b]=1
AB[b,a]=1
end

ppp=[i for i=1:N]

function friends(i,s)
    new=setdiff(Set(ppp[AB[i,:]]),s)
    s=union(s,new)
    for j in new
        s=friends(i,s)
    end
    return s
end

function solve() 
res=0
for i =1:N
s=Set([i])
res=max(res,length(friends(i,s)))
end
print(res)
end
solve()