1a

n=int(input())
a = []
for i in range(n):
    a += [int(input())]
maxx=a[0]+a[7]
for i in range(n-6):
    for j in range(i+7,n):
        if a[i]+a[j]>maxx:
            maxx=a[i]+a[j]
print(maxx)