#include<iomanip>
#include<iostream>
#include<cstdio>
#include<vector>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<ctime>
#include<map>
#include<set>
#include<queue>
#include<algorithm>

using namespace std;

int A, B;
long long put[15];

long long solve (int lim)
{
    if (lim == 0) return 0;
    int nr = 0, v[109];
    while (lim) v[++nr] = lim % 10, lim /= 10;
    reverse (v + 1, v + nr + 1);
    int bef = 0;
    long long ans = 0;
    for (int i=1; i<=nr; i++)
    {
        int aft = 0;
        for (int p=i + 1; p<=nr; p++)
            aft = aft * 10 + v[p];
        for (int j=1; j<10; j++)
        {
            long long coef = bef;
            if (i < nr) coef = 1LL * coef * put[nr - i - 1] * 5;
            else coef = 1LL * coef * (j % 2 == 1);
            if (i == nr && j % 2 == 0) continue;
            if (j <= v[i])
            {
                if (i != nr)
                {
                    if (j == v[i]) coef += (aft + 1) / 2;
                    else coef += 1LL * put[nr - i - 1] * 5;
                }
                else coef ++;
            }
//            if (coef != 0) printf ("%d %d de %lld ori\n", i, j, coef);
            ans += 1LL * j * coef;
        }
        bef = bef * 10 + v[i];
    }
    return ans;
}

int brute (int val)
{
    int sol = 0;
    for (int i=1; i<=val; i+=2)
    {
        int aux = i;
        while (aux) sol += aux % 10, aux /= 10;
    }
    return sol;
}

void Eval ()
{
    int sol = 0;
    for (int i=1; i<=10000000; i++)
    {
        if (i & 1)
        {
            int aux = i;
            while (aux) sol += aux % 10, aux /= 10;
        }
        if (sol != solve (i))
        {
            printf ("wa %d\n", i);
            return ;
        }
    }
}

int main()
{
//freopen ("input", "r", stdin);
//freopen ("output", "w", stdout);

scanf ("%d %d", &A, &B);
put[0] = 1;
for (int i=1; i<=10; i++)
    put[i] = 1LL * put[i - 1] * 10;
//printf ("%d\n", brute (B));
//Eval ();
//return 0;
long long ans = solve (B) - solve (A - 1);
printf ("%lld\n", ans);

return 0;
}