#! ruby
# yukicoder My Practice
# author: Leonardone @ NEETSDKASU

def gi(); gets.to_i; end
def gis(); gets.chomp.split.map(&:to_i); end

n, m = gis


# 連結成分を検出するためラベリング（？）

grp = [0] * (n + 1)
grp_c = 0
grp_r = []
grp_n = [0]

grp[0] = 1

m.times do
    u, v = gis
    next if u == v
    gu, gv = grp[u], grp[v]
    if gu == 0
        if gv == 0
            grp[u] = grp[v] = grp_c += 1
            grp_r << {grp_c => 1}
            grp_n << 2
        else
            grp[u] = gv
            grp_n[gv]+= 1
        end
    elsif gv == 0
        grp[v] = gu
        grp_n[gu] += 1
    elsif gu != gv
        ui, vi = [gu,gv].map{|k| grp_r.index{|o| o.key? k} }.minmax
        grp_r[ui].merge! grp_r[vi]
        grp_r.delete_at vi
    end
end

grp_f = grp_r.inject( [nil]*(grp_c + 1) ){|r, a| k = a.keys; k.each{|x| r[x] = k}; r }

dp = [0] * (n + n)

dp[0] = 1
dp[1] = 2 if grp.include? 0

(1..grp_c).each do |i|
    c = 1
    if grp_f[i].nil?
        c = grp_n[i] 
    else
        c = grp_f[i].inject(0){|r, j| r + grp_n[j]}
        grp_f[i].clear
    end
    (n-1).downto(0) do |j|
        next if dp[j] == 0
        if dp[j + c] == 0
            dp[j + c] = dp[j] + 1
        elsif dp[j] + 1 < dp[j + c]
            dp[j + c] = dp[j] + 1
        end
    end
end

puts dp[1..n].map{|v| v > 0 ? v - 2 : -1} * $/