@x=[]
a=[]
@t=[]
n,k = gets.chomp.split(" ").map(&:to_i)
@x+=gets.chomp.split(" ").map(&:to_i)
a+=gets.chomp.split(" ").map(&:to_i)
@hash = Hash[*([@x,a].transpose.flatten)]

@c=0

p=@x[k-1]
b=a[k-1]

def f(p,w)
  b = @hash[p]
  zzz = p+w*b
  zzz1 = p+(-1*w*b)
  @x.each do |elm|
    if zzz1 > zzz
      if elm >=zzz and zzz1 >= elm
        if @t.any? {|w| w == elm }
          next
        else
          @t.push(elm)
        end
        f(elm,1)
        f(elm,-1)
      end
    else
      if zzz >= elm and elm >= zzz1
        if @t.any? {|w| w == elm }
          next
        else
          @t.push(elm)
        end
        f(elm,1)
        f(elm,-1)
      end
    end
  end
  @c+=1
end

f(p,1)
f(p,-1)

@t=[0] if @t==nil
p @t.length