#include <iostream>
#include <string>
#include <cstring>

using namespace std;

int main()
{
    int a, b, s = 0;
    cin >> a >> b;
    if(!(a&1))
        ++a;
    for(int i = a; i <= b; i += 2)
    {
        int x = i;
        while(x > 0)
        {
            s += x%10;
            x /= 10;
        }
    }
    cout << s;
}