# -*- coding: utf-8 -*-

n = int(eval(input()))

a1 = [int(i) for i in input().split()]

a2 = [int(i) for i in input().split()]

"""

ans = 0

tmp = 0

for i in range(n):

    tmp = sum(a1[0:i+1]) + sum(a2[i:n])

    #print(sum(a1[0:i+1]))

    #print(sum(a2[i:n]))

    if ans < tmp:

        ans = tmp

print(ans)

"""

ans = 0

for i in range(n):

    tmp = 0

    for j in range(i + 1):

        tmp += a1[j]

    for j in range(i, n):

        tmp += a2[j]

    #print(tmp)

    if ans < tmp:

        ans = tmp

print(ans)

# -*- coding: utf-8 -*-

n = int(eval(input()))

a1 = [int(i) for i in input().split()]

a2 = [int(i) for i in input().split()]



ans = 0

for i in range(n):

    tmp = sum(a1[:i+1]) + sum(a2[i:])

    if tmp > ans:

        ans = tmp

print(ans)

# -*- coding: utf-8 -*-
n = int(eval(input()))
a1 = [int(i) for i in input().split()]
a2 = [int(i) for i in input().split()]
"""
ans = 0
tmp = 0
for i in range(n):
    tmp = sum(a1[0:i+1]) + sum(a2[i:n])
    #print(sum(a1[0:i+1]))
    #print(sum(a2[i:n]))
    if ans < tmp:
        ans = tmp
print(ans)
"""
ans = 0
for i in range(n):
    tmp = 0
    for j in range(i + 1):
        tmp += a1[j]
    for j in range(i, n):
        tmp += a2[j]
    # print(tmp)
    if ans < tmp:
        ans = tmp
print(ans)

# -*- coding: utf-8 -*-
n = int(eval(input()))
a1 = [int(i) for i in input().split()]
a2 = [int(i) for i in input().split()]
ans = 0
for i in range(n):
    tmp = sum(a1[: i + 1]) + sum(a2[i:])
    if tmp > ans:
        ans = tmp
print(ans)

-""" -tmp = 0 -    tmp = sum(a1[0:i+1]) + sum(a2[i:n]) -    #print(sum(a1[0:i+1])) -    #print(sum(a2[i:n])) -    if ans < tmp: +    tmp = sum(a1[: i + 1]) + sum(a2[i:]) +    if tmp > ans: -""" -ans = 0 -for i in range(n): -    tmp = 0 -    for j in range(i + 1): -        tmp += a1[j] -    for j in range(i, n): -        tmp += a2[j] -    # print(tmp) -    if ans < tmp: -        ans = tmp -print(ans)