n=int(input())

d=[0]*201

score=[]

if(n>0):

    for i in range(0,n):

        score.append(int(input()))

    d[0]=score[0]

    d[1]=max(score[1],score[0]+score[1])

    if(n==1):

        print(d[0])

        exit()

    elif(n==2):

        print(d[1])

        exit()

    for i in range(2,n):

        d[i]=max(d[i-2]+score[i],d[i-3]+score[i-1]+score[i])

    print(d[n-1])

else:

    print(0)

내가 뭘 어떻게 해주면 만족할건데????? 틀린데좀 말해달라고!!! IDLE에선 멀쩡하게 돌아가는데!!!!