import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

n = ni()
a = na()
b = na()
c = na()

inf = 10**18
dp = [[-inf] * 5 for i in range(n+1)]

dp[0] = [0] * 5

for i in range(n):
    dp[i+1][0] = dp[i][0] + a[i]
    dp[i+1][1] = dp[i][1] + b[i]
    dp[i+1][2] = dp[i][2] + c[i]
    dp[i+1][3] = dp[i][3] + b[i]
    dp[i+1][4] = dp[i][4] + a[i]

    for j in range(4):
        dp[i+1][j+1] = max(dp[i+1][j+1], dp[i+1][j])
A = max(dp[n])

inf = 10**18
dp = [[-inf] * 5 for i in range(n+1)]

dp[0] = [0] * 5

for i in range(n):
    dp[i+1][0] = dp[i][0] + a[i]
    dp[i+1][1] = dp[i][1] + b[i]
    dp[i+1][2] = dp[i][2] + a[i]
    dp[i+1][3] = dp[i][3] + b[i]
    dp[i+1][4] = dp[i][4] + a[i]

    for j in range(4):
        dp[i+1][j+1] = max(dp[i+1][j+1], dp[i+1][j])

B = max(dp[n])
print(max(A,B))