import itertools

N = int(input())

input_list = []
for i in range(N):
    n = input()
    comp = n.split()
    if len(comp) == N:
        break
    else:
        input_list.append(int(n))

if len(input_list) == N:
    sums = [sum(c) for c in itertools.combinations(input_list,2)]
    sums = list(set(sums))
    sums.sort()
    if len(sums) == N:
        print(sums[1])
    else:
        print(min(sums))
else:
    print('"assert"')