input = [i.rstrip() for i in open("input").readlines()]
splitted = [i.split('   ') for i in input]

left = [int(i[0]) for i in splitted]
left = sorted(left)
right = [int(i[1]) for i in splitted]
right = sorted(right)

output = []
for index in range(len(left)):
    signed_dist = int(left[index]) - int(right[index])
    output.append(abs(signed_dist))

print(sum(output))