#pragma GCC optimize("Ofast")
#pragma GCC optimize(1)
#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC target("popcnt")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef string str;
typedef pair<ll,ll> pii;
#define F first
#define S second
#define pb push_back
#define pq priority_queue
#define all(x) (x).begin(),(x).end()
#define bug(x) cerr << (x) << '\n'
#define yn(x) cout << (x==1?"Yes\n":"No\n")
#define PI 3.14159265358979323
#define Ststone ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
const ll max_n=2e5+20,max_int=2147483647,mod1=1e9+7,mod2=998244353;
const bool online = 0;
ll dx[8] = {1,0,0,-1,1,1,-1,-1};
ll dy[8] = {0,1,-1,0,1,-1,1,-1};
ll t,n,q,m,a,b,c,d,e,dsu[max_n],dp[max_n];
vector<ll> v,v1,v2,v3,v4,vv;
vector<pii> edge;
char cc;
str s;

ll query(ll dot){
    if(dsu[dot]==dot)
        return dot;
    else
        dsu[dot] = query(dsu[dot]);
    return dsu[dot];
}

void merge(ll a,ll b){
    if(a>b) swap(a,b);
    dsu[b] = a;
}

void solve(){
    cin >> n >> m;
    for(ll i=0;i<max_n;i++)
        dsu[i] = i;
    for(ll i=0;i<m;i++){
        cin >> a >> b;
        edge.pb({a,b});
    }
    for(ll i=m-1;i>=0;i--){
        ll x = edge[i].F,y = edge[i].S;
        //cerr << query(x) << ' ' << query(y) << '\n';
        if(query(x)==query(y)){
            dp[query(x)]++;
        }
        else{
            ll sum = max(dp[query(x)],dp[query(y)])+1;
            merge(query(x),query(y));
            dp[query(x)] = sum;
        }
    }
    ll cnt = 0;
    for(ll i=1;i<=n;i++){
        cnt = max(dp[query(i)],cnt);
        dp[query(i)] = 0;
    }
    cout << cnt << '\n';
}

int main(){
    Ststone;
    if(online){
        #ifndef ONLINE_JUDGE
        freopen("input.txt","r",stdin);
        freopen("output.txt","w",stdout);
        #else
        #endif
    }
    //cin >> t;
    t = 1;
    for(ll i=1;i<=t;i++){
        //cout << "Case #"<<i<<": ";
        solve();
    }
}


/*

*/