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

output=B[0]
for i in range(1,N):
    if i==N-1:
        output+=B[i]
    else:
        output+=B[i]+C[i]
print(output)