/* 
 * File:   main.cpp
 * Author: student
 *
 * Created on April 15, 2016, 4:04 PM
 */

#include <cstdlib>
#include <iostream>
#include <cmath>

using namespace std;

/*
 * 
 */

int f_min(int a, int b) {
    return a < b ? a : b;
}

int main(int argc, char** argv) {

    long a, b, sum;

    cin >> a >> b;

    if ((a + 1) % 2) a++;
    if ((b + 1) % 2) b--;

    for (int iii = a; iii <= b; iii += 2) {
        for (int jjj = 0; jjj < log(iii); jjj++) {
            int digit = iii / pow(10, jjj);
            digit = digit % 10;
            sum += digit;
        }
    }

    cout << sum;


    return 0;
}