from ctypes import Union


class Unionfind:
     
    def __init__(self,n):
        self.uf = [-1]*n
        self.score = [0]*n
 
    def find(self,x):
        if self.uf[x] < 0:
            return x
        else:
            self.uf[x] = self.find(self.uf[x])
            return self.uf[x]
 
    def same(self,x,y):
        return self.find(x) == self.find(y)
 
    def union(self,x,y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            self.score[self.find(x)] += 1
            return False
        if self.uf[x] > self.uf[y]:
            x,y = y,x
        self.uf[x] += self.uf[y]
        self.score[x] = max(self.score[x],self.score[y])+1
        self.uf[y] = x
        return True
 
    def size(self,x):
        x = self.find(x)
        return -self.uf[x]

n,m = map(int,input().split())
Edges = [[int(x)-1 for x in input().split()] for i in range(m)]

uf = Unionfind(n)

for u,v in Edges[::-1]:
    uf.union(u,v)
    # print(uf.score)

print(max(uf.score))