N = int(eval(input()))

import numpy as np

A = np.array([[int(x) for x in input().split()],[int(x) for x in input().split()]], dtype='int64')

A = A.cumsum(axis=1)

Ans = [A[0,i]+A[1,N-1]-A[1,i-1] if i > 0 else A[0,i]+A[1,N-1] for i in range(N)]

print((max(Ans)))


def main():

    with open(0) as f:

        N = int(f.readline())

        A = list(map(int, f.readline().split()))

        B = list(map(int, f.readline().split()))



    ans = max([sum(A[:i+1]+B[i:]) for i in range(N)])

    print(ans)



main()
N = int(eval(input()))
import numpy as np

A = np.array(
    [[int(x) for x in input().split()], [int(x) for x in input().split()]],
    dtype="int64",
)
A = A.cumsum(axis=1)
Ans = [
    A[0, i] + A[1, N - 1] - A[1, i - 1] if i > 0 else A[0, i] + A[1, N - 1]
    for i in range(N)
]
print((max(Ans)))

def main():
    with open(0) as f:
        N = int(f.readline())
        A = list(map(int, f.readline().split()))
        B = list(map(int, f.readline().split()))
    ans = max([sum(A[: i + 1] + B[i:]) for i in range(N)])
    print(ans)


main()

-N = int(eval(input())) -import numpy as np +def main(): +    with open(0) as f: +        N = int(f.readline()) +        A = list(map(int, f.readline().split())) +        B = list(map(int, f.readline().split())) +    ans = max([sum(A[: i + 1] + B[i:]) for i in range(N)]) +    print(ans) -A = np.array( -    [[int(x) for x in input().split()], [int(x) for x in input().split()]], -    dtype="int64", -) -A = A.cumsum(axis=1) -Ans = [ -    A[0, i] + A[1, N - 1] - A[1, i - 1] if i > 0 else A[0, i] + A[1, N - 1] -    for i in range(N) -] -print((max(Ans))) + +main()