x,y=map(int,raw_input().split())
x2,y2=map(int,raw_input().split())
ans=max(x,y)
if x==0 and x2==0 and y2<y:
    ans+=1
if y==0 and y2==0 and x2<x:
    ans+=1
if x==y and x2==y2 and x2<x:
    ans+=1
print ans