import sys
input = lambda : sys.stdin.readline().rstrip()

sys.setrecursionlimit(2*10**5+10)
write = lambda x: sys.stdout.write(x+"\n")

a,b,c,d = list(map(int, input().split()))
if a==c or b==d or abs(a-c)+abs(b-d)<=3:
    ans = 1
else:
    ans = 2
print(ans)