#include <cstdio>
#include <algorithm>
#include <vector>
#include <climits>
#include <cmath>

#define f first
#define s second

using namespace std;

long long sum, ssum[16], nr[16];
int n, lim;

void bac (int p)
{
    if (p == 1) sum = ssum[1] = 25LL, nr[1] = 5LL;
    if (p == lim)
    {
        int v[16], k = 0;

        while (n)
        {
            v[++k] = n % 10;
            n /= 10;
        }

        long long t = 0LL;
        for (int i = k; i > 1; --i)
        {
            for (int j = 1; j < v[i]; ++j)
                sum += ssum[i - 1] + 1LL * (1LL * j + t) * nr[i - 1];

            t += 1LL * v[i];
        }

        for (int i = 1; i <= v[1]; i += 2)
            sum += 1LL * i + t;

        return;
    }

    if (p > 1) ssum[p] = sum = 10LL * sum + 45LL * nr[p - 1], nr[p] = 10LL * nr[p - 1];

    bac (p + 1);
}

int main ()
{
  //  freopen ("file.in", "r", stdin);

    int a, b;
    scanf ("%d %d", &a, &b);

    n = b;
    lim = ((int)log10(1.0 * b)) + 1;

    if (lim > 1) bac (1);
    else
    {
        sum = 0;
        for (int i = 1; i <= b; i += 2)
            sum += 1LL * i;
    }

    long long x = sum;

    n = a - 1;
    lim = ((int)log10(1.0 * (a - 1))) + 1;

    if (lim > 1) bac (1);
    else
    {
        sum = 0;
        for (int i = 1; i < a; i += 2)
            sum += 1LL * i;
    }

    x -= sum;

    printf ("%lld\n", x);

    return 0;
}