#include<iostream>
using namespace std;
unsigned long long a,b,s,c;
unsigned long long v[10];
int main()
{
    cin>>a>>b;
    a+=((a%2)+1)%2;
    if(b%2==0)
        b--;
    for(;a<=b;a+=2)
    { c=a;
        while(c)
        {
            v[c%10]++;
            c/=10;
        }
    }
    for(c=1;c<=9;++c)
       s+=v[c]*c;
    cout<<s;
    return 0;
}