## main

n, m = gets.strip.split(' ').map{|s| s.to_i}

as = n.times.map{gets.strip.to_i}
bs = m.times.map{gets.strip.to_i}

votes = n.times.map{0}

for bj in bs
  for i in (0...n)
    if as[i] <= bj
      votes[i] += 1
      break
    end
  end
end
#p votes

max_v = 0
max_i = nil

for i in (0...n)
  if max_v < votes[i]
    max_v = votes[i]
    max_i = i
  end
end

puts (max_i + 1)