def Odd():
    sum = 0
    a = int(input())
    b = int(input())
    if a%2==0:
        a+=1
    if b%2!=0:
        b+=1
    for i in range(a,b,2):
        n = i
        r = 0
        while n:
            r, n = r + n % 10, n // 10
        sum += r
    print(sum)

Odd()