from array import array
X=array("i")
N=int(input())
S=0
X=[0]*N
for i in range(0,N):
X[i]=int(input())
for i in range(0,N):
if X[i]%2==0 and i%2==1:
S+=X[i]
print(S)
ZnJvbSBhcnJheSBpbXBvcnQgYXJyYXkKWD1hcnJheSgiaSIpCk49aW50KGlucHV0KCkpClM9MApYPVswXSpOCmZvciBpIGluIHJhbmdlKDAsTik6CiAgICBYW2ldPWludChpbnB1dCgpKQpmb3IgaSBpbiByYW5nZSgwLE4pOgogICAgaWYgWFtpXSUyPT0wIGFuZCBpJTI9PTE6CiAgICAgICAgUys9WFtpXQpwcmludChTKQ==