#include <iostream>
#include <cstdio>

using namespace std;

const int lim = 100000;

int sum[lim];

int sumBrut(int x) {
    int ret = 0;

    while(x) {
        ret += x % 10;
        x /= 10;
    }
    return ret;

}

int sumDigits(int x) {
    int ret = 0;
    ret += sum[x % lim];
    x /= lim;
    return ret + sum[x];
}

int main() {
    for(int i = 0; i < lim; ++i)
        sum[i] = sumBrut(i);

    int a, b;
    cin >> a >> b;

    long long dat = 0;

    a += !(a % 2);
    b -= !(b % 2);


    int up = lim;

    if(up >= b)
        up = b + 1;

    for(int i = a; i < up; i += 2)
        dat += sum[i];

    for(int i = lim + 1; i <= b; i += 2)
        dat += sumDigits(i);

    cout << dat << "\n";

    return 0;
}