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

count = 0

1000.times do |i|
	n, k = gets.split.map(&:to_i)
	if (n.even? && k.even?) || (n.odd? && k.odd?)
		count += 1
	end
end

puts 1000 - count

=begin

N=5 K=3
S
1
 L   S
 234 5
S
12
  L  S
  34 5
S
123
  L S
  4 5
  
N=6 K=3
S
1
 L S   L
 2 345 6
 L   S L  
 234 5 6
 L  S  L
 23 45 6

N=5 K=4
S    L
1234 5

N=6 K=4
S L    S
1 2345 6
S    L S
1234 5 6

N=7 K=3
S L S   L S
1 2 345 6 7
12 345 6 7


=end