require 'dsu'

data = $stdin.read.split.map(&:to_i)
n = data[0]
m = data[1]
d = DSU.new(n)
m.times do |i|
  d.merge(data[2 + 2 * i], data[3 + 2 * i])
end
puts (0...n).count { |i| d.leader(i) == i }