N, M = gets.split(" ").map{|s| s.to_i}

lr = []
M.times {
	lr << gets.split(" ").map{|s| s.to_i}
}

lr.sort!

maxr = -Float::INFINITY
cnt = N

lr.each {|l, r|
	if l > maxr then
		cnt -= 1
		maxr = r
	elsif r < maxr
		r = maxr
	end
}

puts cnt