from collections import defaultdict
import sys
from typing import Counter
readline=sys.stdin.readline
write=sys.stdout.write
from math import gcd as GCD
import math

readline()
S=list(map(int,readline().split()))
G=list(map(int,readline().split()))
ans=abs(S[0]-G[0])+abs(S[1]-G[1])
print(ans)