#include <bits/stdc++.h>
#include <atcoder/dsu>
#include <atcoder/modint>
using namespace std;
using mint = atcoder::static_modint<998244353>;
template <class F> class y_combinator {
	F f;

  public:
	y_combinator(F&& f) : f(std::forward<F>(f)) {}
	template <class... Args> auto operator()(Args &&... args) const { return f(*this, std::forward<Args>(args)...); }
};
using ll = long long;
using ld = long double;
template <class T, class U = std::less<T>> using prique = std::priority_queue<T, std::vector<T>, U>;
template <class T> T floor(T a, T b) { return a / b - (a % b && (a ^ b) < 0); }
template <class T> T ceil(T a, T b) { return floor(a + b - 1, b); }
template <class T> bool chmin(T& x, const T& y) { return (x > y ? x = y, true : false); }
template <class T> bool chmax(T& x, const T& y) { return (x < y ? x = y, true : false); }
#define overload4(a, b, c, d, e, ...) e
#define rep1(a) for (long long _i = 0; _i < (a); _i++)
#define rep2(i, a) for (long long i = 0; i < (a); i++)
#define rep3(i, a, b) for (long long i = (a); i < (b); i++)
#define rep4(i, a, b, c) for (long long i = (a); i < (b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep(i, a, b, c) for (long long i = (a); i > (b); i += (c))
#define all(x) std::begin(x), std::end(x)
#define rall(x) std::rbegin(x), std::rend(x)
#define pb push_back

void run_case() {
	int N, M;
	cin >> N >> M;
	vector<pair<int,int>> E;
	rep(i, M) {
		int a, b;
		cin >> a >> b;
		a--, b--;
		E.pb({a, b});
	}
	vector<int> A(N);
	atcoder::dsu uf(N);
	rrep(i, M - 1, -1, -1) {
		auto[a,b]=E[i];
		int la = uf.leader(a), lb = uf.leader(b);
		if(la != lb) {
			int p = uf.merge(la, lb);
			int q = p ^ la ^ lb;
			A[p] = max(A[la], A[lb]) + 1;
			A[q] = 0;
		}else {
			A[la] += 1;
		}
	}
	int ans = 0;
	rep(i, N) chmax(ans, A[i]);
	cout << ans << endl;
}

int main() {
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(nullptr);
	std::fixed(std::cout).precision(16);
	int T = 1;
	//cin >> T;
	while(T--) run_case();
	return 0;
}