n=int(input())
a=list(map(int,input().split()))
if len(a)>1:
	print("\"assert\"")
	exit()
for i in range(2):
	a+=[int(input())]
t=set()
for i in range(3):
	for j in range(i+1,3):
		t.add(a[i]+a[j])
t=list(t)
t.sort()
print(t[-2])