#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001



int main(){
	
	int N,M;
	cin>>N>>M;
	
	vector<vector<int>> a(N);
	rep(i,N){
		a[i].push_back(i);
	}
	
	dsu D(N);
	int ans = 0;
	vector<int> x(M),y(M);
	rep(i,M){
		cin>>x[i]>>y[i];
		x[i]--,y[i]--;
	}
	vector<int> cnt(N,0);
	for(int i=M-1;i>=0;i--){
		int X = D.leader(x[i]),Y=  D.leader(y[i]);
		if(X==Y){
			cnt[X]++;
		}
		else{
			D.merge(X,Y);
			int Z = D.leader(x[i]);
			cnt[Z] = max(cnt[X],cnt[Y])+1;
		}
	}
	rep(i,N){
		ans = max(ans,cnt[i]);
	}
	
	cout<<ans<<endl;
	
	
	return 0;
}