A,B,C,D = map(int,input().split())
if A == C or B == D:
    print(1)
    exit()
dx = [-1, 1,-2,-1, 1, 2,-2,-1, 1, 2,-1, 1]
dy = [ 2, 2, 1, 1, 1, 1,-1,-1,-1,-1,-2,-2]
M = len(dx)
for i in range(M):
    if A + dx[i] == C and B + dy[i] == D:
        print(1)
        exit()
print(2)