#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define rep1(i, n) for (int i = 1; i < (int)(n+1); i++)
#define repn(i,a,b) for (int i = (int)(a) ; i < (int)(b+1); i++)
#define repv(i, n) for (ll i = (ll)(n-1); i >= 0; i--)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define sz(x) ((int)(x).size())
#define cauto const auto&
#define bit(n) (1LL<<(n))
#define uni(v) v.erase( unique(v.begin(), v.end()), v.end() );
using ll = long long;
using P = pair<ll,ll>;
using PP = pair<int, P>;
using Graph = vector<vector<int>>;
using mint = modint998244353;
#ifdef LOCAL
    #include <debug.hpp>
    #define debug(...) debug::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
    #define debug(...) (static_cast<void>(0))
#endif

int main(){
    ll n,m;
    cin >> n >> m;
    vector<P> uv;
    rep(i,m){
        ll u,v;
        cin >> u >> v;
        u--; v--;
        uv.push_back({u,v});
    }
    dsu d(n);
    vector<ll> ans(n,0);
    repv(i,m){
        if(d.same(uv[i].first,uv[i].second)){
            ans[d.leader(uv[i].first)]++;
            continue;
        }
        d.merge(uv[i].first,uv[i].second);
        ans[d.leader(uv[i].first)] = max(ans[d.leader(uv[i].first)] ,ans[d.leader(uv[i].second)])+1;
    }
    cout << *max_element(all(ans)) << endl;
    return 0;
}