n,m=map(int,input().split())
e=[]
for i in range(m):
  a,b=map(int,input().split())
  a-=1
  b-=1
  e+=[(a,b)]

def root(x):
  p=x
  l=[p]
  while r[p]!=p:
    p=r[p]
    l+=[p]
  for p in l:
    r[p]=l[-1]
  return r[x]

def union(x,y):
  rx=root(x)
  ry=root(y)
  if rx==ry:
    return
  if rx>ry:
    rx,ry=ry,rx
  r[ry]=rx
  return

r=list(range(n))
f=[0]*n
for a,b in e[::-1]:
  ra=root(a)
  rb=root(b)
  p=min(ra,rb)
  if ra==rb:
    f[p]+=1
  else:
    f[p]=max(f[ra],f[rb])+1
    union(a,b)
print(f[0])