from collections import defaultdict

class UnionFind:
  def __init__(self, n):
    self.node = [-1 for _ in range(n)]

  def root(self, v):
    if self.node[v] < 0:
      return v

    st = []
    while self.node[v] >= 0:
      st.append(v)
      v = self.node[v]

    for u in st:
      self.node[u] = v

    return v

  def size(self, v):
    v = self.root(v)
    return (- self.node[v])

  def same(self, u, v):
    return self.root(u) == self.root(v)

  def unite(self, u, v):
    ru = self.root(u)
    rv = self.root(v)
    if ru == rv:
      return

    du = self.node[ru]
    dv = self.node[rv]
    if du <= dv:
      self.node[rv] = ru
      self.node[ru] += dv
    else:
      self.node[ru] = rv
      self.node[rv] += du

n, m = map(int, input().split())
edges = []
for _ in range(m):
  u, v = map(int, input().split())
  edges.append((u - 1, v - 1))

uf = UnionFind(n)
cnt = defaultdict(int)
for i in range(m - 1, -1, -1):
  u, v = edges[i]
  if not uf.same(u, v):
    ru = uf.root(u)
    rv = uf.root(v)
    c = max(cnt[ru], cnt[rv])
    uf.unite(ru, rv)
    r = uf.root(ru)
    cnt[r] = c + 1
  else:
    r = uf.root(u)
    cnt[r] += 1

print(max(v for v in cnt.values()))