#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
using namespace std;
long long A, B;
long long put[11];

inline long long Count(long long n)
{
    if(n <= 0)
        return 0;
    long long sol = 0;
    for(int cif = 1; cif < 10; ++cif)
    {
        for(int i = 0; i < 11; ++i)
        {
            if(n / put[i] < cif)
                continue;
            else
            {
                if(n / put[i] == cif)
                {
                    if(i == 0)
                        sol += 1LL * cif * (cif % 2);
                    else
                        sol += 1LL * cif * ((n % put[i] + 1) / 2);
                }
                else
                {
                    if(i == 0)
                    {
                        sol += 1LL * cif * (cif % 2) * (n / put[i + 1]);
                        if(n % 10 >= cif)
                            sol += 1LL * cif * (cif % 2);
                    }
                    else
                    {
                        sol += 1LL * cif * (put[i] / 2LL) * (n / put[i + 1]);
                        if((n / put[i]) % 10 > cif)
                        {
                            sol += 1LL * cif * (put[i] / 2LL);;
                        }
                        else
                        {
                            if((n / put[i]) % 10 == cif)
                            {
                                sol += 1LL * cif * ((n % put[i] + 1) / 2);
                            }
                            else
                            {

                            }
                        }
                    }
                }
            }
        }
    }
    return sol;
}

int main()
{
    int i;
    put[0] = 1;
    for(i = 1; i < 11; ++i)
        put[i] = 10LL * put[i - 1];
    std::ios_base::sync_with_stdio(false);
    cin >> A >> B;
    cout << (Count(B) - Count(A - 1)) << "\n";
    return 0;
}