# your code goes here
#ef su(ln,mi,la):
 #   if ln==1:
    #    return V[ln-1]
N=int(input ())
V=[int(i) for i in input(). split ()]
if V[0]>V[1]:
    ma=V[0]
    la=0
else:
    ma=V[1]
    la=1
    mal=V[0]
for i in range(2,N-1):
    #print(ma)
    if la==0:
        ma+=V[i]
        la=1
    else:
        c=mal+V[i]
        if ma>=c:
            la=0
        else:
            mal=ma
            ma=c
print(ma)