#include <bits/stdc++.h>
using namespace std;

class dsu {
  vector<int> p;
  vector<int> sz;

public:
  dsu(int n) : p(n), sz(n, 1) { iota(p.begin(), p.end(), 0); }

  inline int get(int x) {
    if (x == p[x]) {
      return x;
    }
    return p[x] = get(p[x]);
  }

  inline bool unite(int x, int y) {
    x = get(x);
    y = get(y);
    if (x != y) {
      if (sz[x] < sz[y]) {
        swap(x, y);
      }
      p[y] = x;
      sz[x] += sz[y];
      return true;
    }
    return false;
  }

  inline int size(int x) {
    x = get(x);
    return sz[x];
  }
};

int main() {
  iostream::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  int n, m;
  cin >> n >> m;
  vector<pair<int, int>> A(m);
  for (auto &p : A) {
    int x, y;
    cin >> x >> y;
    x--, y--;
    p = {x, y};
  }
  vector<int> cnt(n);

  reverse(A.begin(), A.end());

  dsu uf(n + 1);
  for (auto [x, y] : A) {
    int px = uf.get(x), py = uf.get(y);
    uf.unite(x, y);
    if (px == py) {
      cnt[uf.get(x)] = cnt[px] + 1;
    } else {
      cnt[uf.get(x)] = max(cnt[px], cnt[py]) + 1;
    }
  }

  cout << *max_element(cnt.begin(), cnt.end()) << '\n';

  return 0;
}