import sys
import math

# Auto-generated code below aims at helping you parse
# the standard input according to the problem statement.
a=0
b=0
for i in input().split():
    x = int(i)
    a+=x
for i in input().split():
    x = int(i)
    b+=x

# Write an action using print
# To debug: print("Debug messages...", file=sys.stderr)

d=a-b

if d > 0:
    print(d*-1)
elif d < 0:
    print(d*-1)
else:
    print(d)