#include <iostream>

using namespace std;

int main ()
{
    long long a,b,cop;
    int s;
    cin>>a>>b;
    s=0;
    if (a%2==0) a++;
    if (b%2==0) b--;
    for (int i=a; i<=b; i+=2)
    {
        cop=i; while (cop) {s+=cop%10; cop/=10;}
    }
    cout<<s;
}