n, m = gets.chomp.split(" ").map(&:to_i)
hash = Hash.new(0)
count = 0
iru = Hash.new(0)
n.times do
    b, c = gets.chomp.split(" ").map(&:to_i)
    count += 1 if hash[c] >= 1
    count -= 1 if iru[c] == b
    iru[c] = b
    hash[c] += 1
end
puts count