example = """
3   4
4   3
2   5
1   3
3   9
3   3
"""


parsed = [[],[]]

for x in open('input.txt', 'r').readlines():
    if x:
        a = [y for y in x.split(" ") if y]
        
        parsed[0].append(a[0])
        parsed[1].append(a[1])
        
parsed[0] = sorted(parsed[0])
parsed[1] = sorted(parsed[1])

asd = []

for x, y in zip(parsed[0], parsed[1]):
    x = int(x)
    y = int(y)
    if x > y:
        asd.append(x-y)
    else:
        asd.append(y-x)

num = sum(asd)
print(num)