# 辺の追加
def solve(i, u, k)
    return if i >= $r.length
    ur = u + $r[i]
    return if $memo[ur - 1] >= 0
    $memo[ur - 1] = k
    solve(i + 1, u, k)
    solve(i + 1, ur, k + 1)
end
$n, m = gets.split.map(&:to_i)
#n = 2 * 10 ** 5
#m = 2 * 10 ** 5
a = Hash.new{|h, k| h[k] = Array.new}
b = Array.new($n, false)
#n.times do |i|
#    a[2 * i + 1].push(2 * i + 2)
#    a[2 * i + 2].push(2 * i + 1)
#end
m.times do |i|
    s = gets.split.map(&:to_i)
    next if s[0] == s[1]
    a[s[0]].push(s[1])
    a[s[1]].push(s[0])
end
$r = Array.new
$memo = Array.new($n, -1)
stack = Array.new(m + 10)
$n.times do |i|
    i += 1
    next if b[i]
    top = 1
    bottom = 0
    stack[0] = i
    count = 1
    while bottom < top do
        j = stack[top - 1]
        if !a.has_key?(j)
            top -= 1
            next
        end
        b[j] = true
        a[j].each do |x|
            next if b[x]
            b[x] = true
            stack[top] = x
            top += 1
            count += 1
        end
        bottom += 1
    end
    $r.push(count)
end
$r.sort!{|a, b| b <=> a}
solve(0, 0, 0)
puts $memo