N=int(input ())
V=[int(i) for i in input(). split ()]
if N==1:
    ma=V[0]
elif V[0]>V[1]:
    ma=V[0]
    la=0
else:
    ma=V[1]
    la=1
    mal=V[0]
for i in range(2,N):
   # print(ma)
 #   print (mal)
    if la==0:
        mal=ma
        ma+=V[i]
        la=1
    else:
        c=mal+V[i]
        if ma>=c:
            la=0
        else:
            mal=ma
            ma=c
            la=1
print(ma)