#include <bits/stdc++.h>

using namespace std;

long long dp[2][15];
long long sum[2][15];

int x[15];

long long solve(int val) {
    memset(dp, 0, sizeof(dp));
    memset(sum, 0, sizeof(sum));

    int nr = 0;
    while (val) {
        x[++nr] = val % 10;
        val /= 10;
    }
    int st = 1, dr = nr;
    while (st <= dr) {
        swap(x[st], x[dr]);
        ++st;
        --dr;
    }
    dp[1][0] = 1;
    for (int i = 0; i < nr; ++i)
        for (int pot = 0; pot <= 1; ++pot) {
            for (int c = 0; c <= 9; ++c) {
                if (pot == 1 && c > x[i + 1])
                    continue;
                if (c % 2 == 0 && i == nr - 1)
                    continue;
                int new_pot = pot;
                if (c < x[i + 1])
                    new_pot = 0;
                dp[new_pot][i + 1] += dp[pot][i];
                sum[new_pot][i + 1] += sum[pot][i] + c * dp[pot][i];
            }
        }
    return sum[0][nr] + sum[1][nr];
}

int main() {
    int a, b;
    cin >> a >> b;
    long long res = solve(b) - solve(a - 1);
    cout << res;
    return 0;
}