ХУЙ

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <deque>
#include <set>
#include <map>
#include <climits>
#include <cstdlib>
#include<time.h>
#include<iomanip>
using namespace std;
long long a,b, step[12];

long long BuildN(int (&dig)[12]) {
	long long answ=0;
	for (int i = 0; i <= 10; i++) {
		answ += step[i] * dig[i];
	}
	return answ;
}

long long Kolvo(long long a) {
	long long a2 = a;
	int dig[12];
	for (int i = 10; i >= 0; i--) {
		dig[i] = a2 / step[i];
		a2 %= step[i];
	}
	int sum = 0, otv = 0;
	for (int i = 10; i >= 0; i--) {
		otv += dig[i] * step[i] / 2;
		if (sum % 2 == 0 && dig[i]%2 == 1) {
			otv++;
		}
		if (sum % 2 == 1 && dig[i]%2 == 1 && i!=0) {
				otv--;
		}
		if (sum % 2 == 0 && dig[i] % 2 == 0) {

		}
		if (sum % 2 == 1 && dig[i] % 2 == 0) {
			//otv--;
		}
		//cout << dig[i] << "!" << otv << "\n";
		sum += dig[i];
	}
	return otv;
}


int main() {
	std::ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	step[0] = 1;
	for (int i = 1; i < 12; i++) {
		step[i] = step[i - 1] * 10;
	}
	cin >> a >> b;
	cout << Kolvo(b) - Kolvo(a-1);
}