m,n=map(int,input().split())

xx = list(map(int,input().split()))#学校

xs = list(map(int,input().split()))#学生

xs.sort()#排序

xx.sort()

s=0

for i in xs:#学生

	ans=999999
	left=0
	right=len(xx)-1
	while(left<=right):
    	mid = (left+right)//2
    	if(xx[mid]==i):
          ans=0
          break
      elif(xx[mid]<i):
              ans = min(ans,abs(xx[mid]-i))#最小值
              left = mid+1
    elif(xx[mid]>i):
            ans = min(ans,abs(xx[mid]-i))
            right = mid-1 
s=s+ans

print(s)