# cook your dish here
a = int(input())
b = int(input())
c = int(input())
d = int(input())
e = int(input())
f = int(input())
sum = a + b + c + d + e + f
print(sum // 6)
IyBjb29rIHlvdXIgZGlzaCBoZXJlCmEgPSBpbnQoaW5wdXQoKSkKYiA9IGludChpbnB1dCgpKQpjID0gaW50KGlucHV0KCkpCmQgPSBpbnQoaW5wdXQoKSkKZSA9IGludChpbnB1dCgpKQpmID0gaW50KGlucHV0KCkpCgpzdW0gPSBhICsgYiArIGMgKyBkICsgZSArIGYKcHJpbnQoc3VtIC8vIDYp