### BUGGY CODE ###

from bisect import *
from collections import *
from itertools import *
import functools
import sys
import math
from decimal import *
from copy import *
from heapq import *
from fractions import *
getcontext().prec = 30
MAX = sys.maxsize
MAXN = 1000010
MOD = 10**9+7
spf = [i for i in range(MAXN)]
spf[0]=-1
def sieve():
    for i in range(2,MAXN,2):
        spf[i] = 2
    for i in range(3,int(MAXN**0.5)+1):
        if spf[i]==i:
            for j in range(i,MAXN,i):
                if spf[j]==j:
                    spf[j]=i
def fib(n,m):
    if n == 0:
        return [0, 1]
    else:
        a, b = fib(n // 2)
        c = ((a%m) * ((b%m) * 2 - (a%m)))%m
        d = ((a%m) * (a%m))%m + ((b)%m * (b)%m)%m
        if n % 2 == 0:
            return [c, d]
        else:
            return [d, c + d]
 
def charIN(x= ' '):
    return(sys.stdin.readline().strip().split(x))
 
def arrIN(x = ' '):
    return list(map(int,sys.stdin.readline().strip().split(x)))
 
def ncr(n,r):
    num=den=1
    for i in range(r):
        num = (num*(n-i))%MOD
        den = (den*(i+1))%MOD
 
    return (num*(pow(den,MOD-2,MOD)))%MOD
 
def flush():
    return sys.stdout.flush()




'''*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*'''

def bfs(v):
    q = [v]
    vis[v] = 1
    l = 0
    while q:
        x = q.pop(0)
        l+=1
        for i in d[x]:
            if not vis[i]:
                vis[i] = 1
                q.append(i)
    return l


n,m = arrIN()
d = defaultdict(set)

for _ in range(m):
    a,b = arrIN()
    d[a].add(b)
    d[b].add(a)

vis = defaultdict(int)
cc = []
for i in range(1,n+1):
    if not vis[i]:
        cc.append(bfs(i))

cc.sort()
ans = cc[0]
cl = cc[0]
t = cl
for i in cc[1:]:
    if i==cl:
        continue
    cl = i-t
    t+=cl
    ans+=cl
print(ans)



### FIXED CODE ###

from bisect import *
from collections import *
from itertools import *
import functools
import sys
import math
from decimal import *
from copy import *
from heapq import *
from fractions import *
getcontext().prec = 30
MAX = sys.maxsize
MAXN = 1000010
MOD = 10**9+7
spf = [i for i in range(MAXN)]
spf[0]=-1
def sieve():
    for i in range(2,MAXN,2):
        spf[i] = 2
    for i in range(3,int(MAXN**0.5)+1):
        if spf[i]==i:
            for j in range(i,MAXN,i):
                if spf[j]==j:
                    spf[j]=i
def fib(n,m):
    if n == 0:
        return [0, 1]
    else:
        a, b = fib(n // 2)
        c = ((a%m) * ((b%m) * 2 - (a%m)))%m
        d = ((a%m) * (a%m))%m + ((b)%m * (b)%m)%m
        if n % 2 == 0:
            return [c, d]
        else:
            return [d, c + d]
 
def charIN(x= ' '):
    return(sys.stdin.readline().strip().split(x))
 
def arrIN(x = ' '):
    return list(map(int,sys.stdin.readline().strip().split(x)))
 
def ncr(n,r):
    num=den=1
    for i in range(r):
        num = (num*(n-i))%MOD
        den = (den*(i+1))%MOD
 
    return (num*(pow(den,MOD-2,MOD)))%MOD
 
def flush():
    return sys.stdout.flush()




'''*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*'''

def bfs(v):
    q = [v]
    vis[v] = 1
    l = 0
    while q:
        x = q.pop(0)
        l+=1
        for i in d[x]:
            if not vis[i]:
                vis[i] = 1
                q.append(i)
    return l


n,m = arrIN()
d = defaultdict(set)

for _ in range(m):
    a,b = arrIN()
    d[a].add(b)
    d[b].add(a)

vis = defaultdict(int)
cc = []
for i in range(1,n+1):
    if not vis[i]:
        cc.append(bfs(i))

cc.sort()
ans = cc[0]
cl = cc[0]
t = cl
for i in cc[1:]:
    if i==cl:
        continue
    cl = i-t
    t+=cl
    ans+=cl
print(ans)