#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;

const int N=10005;
int n,m;
vector <int> G[N];
vector <int> L;
int Cnt[N];
int label[N];
int Q[N];
int F[N];

int main(){
	scanf("%d%d",&n,&m);
	for (int i=1;i<=n;i++) G[i].clear();
	for (int i=0;i<m;i++){
		int x,y;
		scanf("%d%d",&x,&y);
		G[x].push_back(y);
		G[y].push_back(x);
	}
	for (int i=1;i<=n;i++) Cnt[i]=label[i]=0;
	for (int i=n;i>=1;i--){
		int Max=-1;
		int Maxi=-1;
		for (int j=1;j<=n;j++)
			if (label[j]==0 && Cnt[j]>Max){
				Max=Cnt[j];
				Maxi=j;
			}
		label[Maxi]=i;
		Q[i]=Maxi;
		for (vector<int>::iterator it=G[Maxi].begin();it!=G[Maxi].end();it++)
			if (label[*it]==0) Cnt[*it]++;
	}
	int ans=1;
	for (int k=n;k>=1;k--){
		int i=Q[k];
		F[i]=1;
		L.clear();
		for (vector<int>::iterator it=G[i].begin();it!=G[i].end();it++)
			if (label[*it]>label[i]) F[i]++;
		ans=max(ans,F[i]);
	}
	printf("%d\n",ans);
}