require "prime"
N = gets.to_i

rs = Prime.take_while{|i|
  i * i <= N
}

cnt = 0
rs.each{|i|
  r = i*i
  j = 2
  if j <= N && r - j <= N && (r - j).prime?
    cnt += j == r - j ? 1 : 2
  end
}
p cnt