import sys

sys.setrecursionlimit(10 ** 6)
def MI(): return map(int, sys.stdin.readline().split())

def main():
    x,y=MI()
    x2,y2=MI()
    ans=max(x,y)
    if (x==0 and y2<y) or (y==0 and x2<x) or (x==y and x2==y2 and x2<x):ans+=2
    print(ans)

main()