N = int(input())
A = list(map(int, input().split()))
if len(A) == N:
    print("assert")
    exit()
A = [A[0]] + [int(input()) for i in range(N - 1)]
st = set()
for i in range(3):
    for j in range(i + 1, 3):
        st.add(A[i] + A[j])
print(sorted(list(st), reverse = True)[1])