import sys

l1 = []
l2 = []

for l in sys.stdin:
    l = [int(x) for x in l.split()]
    l1.append(l[0])
    l2.append(l[1])

l1.sort()
l2.sort()

s = 0
for i in range(len(l1)):
    s += abs(l1[i] - l2[i])

print(s)