#include<iostream>
using namespace std;
int digitSum(long long x)
{
	int ans = 0;
	while (x > 0)
	{
		ans += x % 10;
		x /= 10;
	}
	return ans;
}
long long solve(long long l, long long r)
{
	if (r - l <= 20)
	{
		long long ans = 0;
		for (long long i = l; i <= r; i++)
		{
			ans += digitSum(i);
		}
		return ans;
	}
	if (l % 10 != 0)
	{
		return digitSum(l) + solve(l + 1, r);
	}
	if (r % 10 != 9)
	{
		return digitSum(r) + solve(l, r - 1);
	}
	return solve(l / 10, r / 10) * 10 + (long long)45LL * ( r / 10 - l / 10 + 1);
}
int main()
{
	long long l, r;
	cin >> l >> r;
	cout << solve(l, r) << endl;
}