# import sys; input = sys.stdin.buffer.readline
# sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	N = int(input())
	A = getlist()
	if sum(A) != A[0]:
		print('"assert"')
		return

	a2 = int(input())
	A.append(a2)
	a3 = int(input())
	A.append(a3)
	A.sort()

	if A[0] + A[2] == A[1] + A[2]:
		print(A[0] + A[1])
	else:
		print(A[0] + A[2])





if __name__ == '__main__':
	main()