from collections import defaultdict, deque
from heapq import heappush, heappop
from itertools import permutations, accumulate
import sys
import math
import bisect
def LI(): return [int(x) for x in sys.stdin.readline().split()]
def I(): return int(sys.stdin.readline())
def IR(n):
    return [I() for _ in range(n)]
def LIR(n):
    return [LI() for _ in range(n)]

sys.setrecursionlimit(1000000)
mod = 1000000007

class UnionFind:

    __slots__ = ["par", "rank", "size"]

    def __init__(self, n):
        self.par = list(range(n))
        self.rank = [0]*n
        self.size = [1]*n

    def root(self, x):
        if x == self.par[x]:
            return x
        self.par[x] = self.root(self.par[x])
        return self.par[x]

    def unite(self, x, y):
        x = self.root(x)
        y = self.root(y)
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
            self.size[y] += self.size[x]
        else:
            self.par[y] = x
            self.size[x] += self.size[y]
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
        return


def main():
    n,m = LI()
    edges = LIR(m)
    uf = UnionFind(n)
    f = [0]*n
    for a,b in reversed(edges):
        a -= 1
        b -= 1
        ra = uf.root(a)
        rb = uf.root(b)
        if ra != rb:
            uf.unite(a,b)
            f[uf.root(a)] = max(f[ra],f[rb])+1
        else:
            f[ra] += 1
    print(max(f))
    return


if __name__ == "__main__":
    main()