import sys
input = sys.stdin.readline

N=int(input())
A=list(map(int,input().split()))
B=list(map(int,input().split()))
C=list(map(int,input().split()))

# 0 1 2 1 0

DP=[[-1<<30]*(N+1) for i in range(5)]
DP[0][0]=0

for i in range(N):
    DP[0][i+1]=DP[0][i]+A[i]

    DP[1][i+1]=max(DP[0][i]+B[i],DP[1][i]+B[i])

    DP[2][i+1]=max(DP[1][i]+C[i],DP[2][i]+C[i])

    DP[3][i+1]=max(DP[3][i]+B[i],DP[2][i]+B[i])

    DP[4][i+1]=max(DP[4][i]+A[i],DP[3][i]+A[i])

ANS=max(DP[0][N],DP[1][N],DP[2][N],DP[3][N],DP[4][N])

# 0 1 0 1 0

DP=[[-1<<30]*(N+1) for i in range(5)]
DP[0][0]=0

for i in range(N):
    DP[0][i+1]=DP[0][i]+A[i]

    DP[1][i+1]=max(DP[0][i]+B[i],DP[1][i]+B[i])

    DP[2][i+1]=max(DP[1][i]+A[i],DP[2][i]+A[i])

    DP[3][i+1]=max(DP[3][i]+B[i],DP[2][i]+B[i])

    DP[4][i+1]=max(DP[4][i]+A[i],DP[3][i]+A[i])

ANS2=max(DP[0][N],DP[1][N],DP[2][N],DP[3][N],DP[4][N])

print(max(ANS,ANS2))