###スニペット始まり###
import sys, re
from math import ceil, floor, sqrt,factorial, gcd, pi, degrees, radians, sin, asin, cos, acos, tan, atan2
from collections import Counter, deque, defaultdict
from heapq import heapify, heappop, heappush
from itertools import permutations, accumulate, product, combinations, combinations_with_replacement
from bisect import bisect, bisect_left, bisect_right
from functools import reduce, lru_cache
from string import ascii_uppercase, ascii_lowercase
from decimal import Decimal, ROUND_HALF_UP #四捨五入用

def input(): return sys.stdin.readline().rstrip('\n')

#easy-testでは再帰数を下げる。
if __file__=='prog.py':
    sys.setrecursionlimit(10**5)
else:
    sys.setrecursionlimit(10**6)

def lcm(a, b): return a * b // gcd(a, b)

#3つ以上の最大公約数/最小公倍数
def gcd_v2(l: list): return reduce(gcd, l)
def lcm_v2(l: list): return reduce(lcm, l)

#nPk
def nPk(n, k): return factorial(n) // factorial(n - k)

#逆元
def modinv(a, mod=10**9+7): return pow(a, mod-2, mod)
INF = float('inf')
MOD = 10 ** 9 + 7
###スニペット終わり###

#0-index
class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)

        if x == y:
            return

        if self.parents[x] > self.parents[y]:
            x, y = y, x

        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

    def same(self, x, y):
        return self.find(x) == self.find(y)

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return len(self.roots())

    def all_group_members(self):
        group_members = defaultdict(list)
        for member in range(self.n):
            group_members[self.find(member)].append(member)
        return group_members

    def __str__(self):
        return '\n'.join(f'{r}: {m}' for r, m in self.all_group_members().items())

N, M = map(int, input().split())

e=[]
for _ in range(M):
    a, b = map(int, input().split())
    e.append([a-1, b-1])

cnt=[0]*N #必要な操作回数
uf=UnionFind(N)

#逆から見ていく。
for a, b in e[::-1]:
    #逆から見る
    if uf.same(a,b):
        cnt[uf.find(a)]+=1 #親に加算
    else:
        pa=uf.find(a)
        pb=uf.find(b)

        uf.union(a,b) #結合
        np=uf.find(a) #新しい親
        cnt[np]=max(cnt[pa], cnt[pb])+1 #更新する
print(max(cnt))