sum = 0

list1 = []
list2 = []

with open("input") as f:
    for line in f.readlines():
        nums = line.split()
        list1.append(int(nums[0]))
        list2.append(int(nums[1]))

list1.sort()
list2.sort()

for ii, num in enumerate(list1):
    sum += abs(num - list2[ii])

print(sum)