#include <iostream>
using namespace std;

int digit(int x){
	int result = x % 10;
	while (x > 0) {
		x/=10;
		result+= x % 10;
	}
	return result;
}

int main()
{
	int a,b,result = 0;
	cin >> a >> b;
	if(a%2 == 0) a++;
	for(int i = a; i <= b; i+=2){
		result += digit(i);
	}
	cout << result;
	return 0;
}