def digsum(n):
    s=0
    while (n>0):
       s+=n%10;
       n=n/10;
    return s;    


S = (raw_input()).split();

a = int(S[0])
b = int(S[1])

s=0
for i in range(a,b+1):
    if i%2==1:
        s+=digsum(i)
        
print s