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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int maxn=2e5+2;
vector<int> adj[maxn],vis(maxn);
int dfs(int v){
    vis[v]=1;
    int ans=1;
    for(int u:adj[v]){
        if(!vis[u]){
            ans+=dfs(u);
        }
    }
    return ans;
}
int main() {
	int n,m;
	cin>>n>>m;
	for(int i=0;i<m;i++){
	    int u,v;
	    cin>>u>>v;
	    adj[u].push_back(v);
	    adj[v].push_back(u);
	}
	int maxi=0;
	for(int i=1;i<=n;i++){
	    if(!vis[i]){
	        maxi=max(maxi,dfs(i));
	    }
	}
	cout<<maxi;
	return 0;
}