promotion-1
Source: hackerearth
Difficulty: MEDIUM

Ramesh is a hard-working employee.Seeing his dedication towards his work his boss decided to promote him. Ramesh was overjoyed on getting to know this.But soon he realized he needed to shift to another Town X. Ramesh needed to transport his n boxes to Town X for which he contacted the company "Packers and Movers".This company sent him m trucks.Each truck took 1 hour to go from his house to Town X and another 1 hour to return.But each truck could carry only 1 box at a time and also each truck has a limit for the maximum weight of the box it can carry.A truck can be used multiple times.  Since Ramesh is busy he gives you the job for finding the minimum time in which he can transfer all his n boxes to Town X.

INPUT
The first line contains 2 integers n and m.The next line contains n integers denoting the weight of each box.This is followed
by a line containing m integers denoting the maximum capacity of each truck.

Output
Print the minimum time to transfer all the boxes to Town X.

Constraints
1 ≤ n,m ≤ 10000
1 ≤ weight of each box ≤ 1000000
1 ≤ maximum capacity of each truck ≤ 1000000

Note:
A solution always exist.

SAMPLE INPUT
7 2
10 2 16 19 6 11 5
29 25

SAMPLE OUTPUT
7

Explanation

The first truck carries the first box and then return to the house in 2 hours again carries the 2nd box and return and again the 
3rd box and return taking a total of 6 hours.

The second truck similarly carries the next 3 boxes and return to the house in 6 hours.

In the 6th hour one of the two truck gets loaded with the 7th box and reaches Town X with the last box at 7th hour.


import sys

n, m = [int(x) for x in sys.stdin.readline().split()]
weights = [int(x) for x in sys.stdin.readline().split()]
trucks = [int(x) for x in sys.stdin.readline().split()]
weights.sort(reverse=True)
trucks.sort(reverse=True)

w = 0
t = 0
count = 1
while (weights):
	#print(w, len(weights))
	if t == len(trucks) or w == len(weights):
		t = 0
		count += 1
		w = 0
		continue
	#print(w, t, count)
	if (weights[w] <= trucks[t]):
		#w += 1
		weights.pop(w)
		t += 1
	else:
		start = w
		end = len(weights) - 1
		while(1):
			if end - start < 2:
				if weights[end] <= trucks[t] and weights[start] >= trucks[t]:
					res = end
				else:
					res = -1
				break
			mid = int((start + end)/2)
			#print(start, end, mid, weights[mid], weights[mid + 1], trucks[t])
			if weights[mid] >= trucks[t] and weights[mid + 1] <= trucks[t]:	
				res = mid
				break
			elif weights[mid] < trucks[t] and weights[mid + 1] < trucks[t]:
				end = mid 
			elif weights[mid] > trucks[t] and weights[mid + 1] > trucks[t]:
				start = mid + 1
		if res == -1:
			t = 0
			count += 1
			w = 0
		else:
			#print('hived', w + 1, res + 1)
			#print('weights of ', res + 1, weights[res + 1], trucks[t])
			w = res + 1
		

print(((count - 1)*2 + 1))