#!/usr/bin/env python3
import sys

MOD = 998244353

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

    

if __name__ == '__main__':
    main()