#include <bits/stdc++.h>

using namespace std;

const int LIM = 1e4;

inline long long int GetSum(const int a, const int &Snum){
    long long int sum = 0;
    int c, start, p;
    if(a < LIM){
        for(int i = 1; i <= a; i += 2){
            c = i;
            while(c){
                sum += c % 10;
                c /= 10;
            }
        }
        return sum;
    }
    for(int i = 1; i * LIM <= a; i++){
        c = i;
        p = 0;
        while(c){
            p += c % 10;
            c /= 10;
        }
        sum += (LIM / 2) * p + Snum;
    }
    start = a / LIM;
    for(int i = start * LIM + 1; i <= a; i += 2){
        c = i;
        while(c){
            sum += c % 10;
            c /= 10;
        }
    }
    return sum;
}

int main(){
    #ifndef ONLINE_JUDGE
    freopen("debug.in", "r", stdin);
    #endif // ONLINE_JUDGE

    int a, b, c;
    long long int Snum = 0;
    cin >> a >> b;
    for(int i = 1; i < LIM; i += 2){
        c = i;
        while(c){
            Snum += c % 10;
            c /= 10;
        }
    }
    cout << GetSum(b, Snum) - GetSum(a - 1, Snum);
    return 0;
}