import sys

sys.setrecursionlimit(10 ** 8)

input = sys.stdin.readline


def main():
    A, B, C, D = [int(x) for x in input().split()]

    if A == C or B == D:
        print(1)
        return

    if abs(A - C) + abs(B - D) <= 3:
        print(1)
        return

    print(2)


    
    

if __name__ == '__main__':
    main()