N=int(input())
V=[int(i) for i in input().split()]

#最大値
dp=[[0 for i in range(N)] for j in range(2)]
dp[0][0]=V[0]
dp[1][0]=0
# print(dp)
for i in range(1,N):
    dp[0][i]=dp[1][i-1]+V[i]
    dp[1][i]=max(dp[0][i-1],dp[1][i-1])

max_value=max(dp[0][N-1],dp[1][N-1])
print(max_value)

#経路探索
# take=0 if dp[0][N-1]>dp[1][N-1] else 1
# path=[]
# for i in reversed(range(N)):
#     if take==0:
#         path.insert(0,True)
#         take=1
#     else:
#         path.insert(0,False)
#         take=0 if dp[0][i-1]>dp[1][i-1] else 1
# print(path)