n=int(input())
a=list(map(int,input().split()))
b=list(map(int,input().split()))
c=list(map(int,input().split()))
X=10**20
ans=0

q=[-X]*3
q[0]=0
for i in range(n):
  nq=[-X]*3
  nq[0]=q[0]+a[i]
  nq[1]=max(q[0],q[1])+b[i]
  nq[2]=q[1]+a[i]
  q=nq
ans=max(ans,max(q))

q=[-X]*5
q[0]=0
for i in range(n):
  nq=[-X]*5
  nq[0]=q[0]+a[i]
  nq[1]=max(q[0],q[1])+b[i]
  nq[2]=max(q[1],q[2])+a[i]
  nq[3]=max(q[2],q[3])+b[i]
  nq[4]=max(q[3],q[4])+a[i]
  q=nq
ans=max(ans,max(q))

q=[-X]*5
q[0]=0
for i in range(n):
  nq=[-X]*5
  nq[0]=q[0]+a[i]
  nq[1]=max(q[0],q[1])+b[i]
  nq[2]=max(q[0],q[1],q[2])+c[i]
  nq[3]=max(q[2],q[3])+b[i]
  nq[4]=max(q[3],q[4])+a[i]
  q=nq
ans=max(ans,max(q))

print(ans)