#!/usr/bin/python

with open('01a.txt') as f:
    text = f.read().strip()

lines = text.split('\n')

a = [0] * len(lines)
b = a[:]

for i in range(len(lines)):
    spl = lines[i].split(' ', maxsplit=1)
    a[i] = int(spl[0].strip())
    b[i] = int(spl[1].strip())

a.sort()
b.sort()

total = 0

for x, y in zip(a, b):
    total += abs(x - y)

print(total)