n, m = gets.split.collect{|x|x.to_i}

cost = []
n.times{
  cost += [gets.to_i]
}

threshold = []
m.times{
  threshold += [gets.to_i]
}

vote = [0] * cost.length

for x in threshold
  for y in 0...cost.length
    if cost[y] <= x then
      vote[y] += 1
      break
    end
  end
end

p vote.index(vote.max) + 1