# list=[]
# n=0
# for i in range(9):
# list.append(int(input()))
# print(max(list))
# print(list.index(max(list))+1)
# list.append(a)
# list.pop()
# max(list)
# min(list)
# sum(list) #모든 값의 합
# list.index(50) #리스트에서 50의 위치
# list=[]
# n=0
# for i in range(7):
# x = int(input())
# if x%2==1 :
# list.append(x)
#
# if len(list)==0:
# print(-1)
# else :
# print(sum(list))
# print(min(list))
list1=[]
n=0
list = list(map(int,input().split()))
for i in range(7):
x = list[i]
if x % 2 == 1:
list1.append(x)
if len(list1)==0:
print(-1)
else :
print(sum(list1))