#include <iostream>
//#include <gtest/gtest.h>

const int FIB_PISANO_PERIOD_FOR_TEN = 60;

static int getFibNModM(long n) {
	long r = n % FIB_PISANO_PERIOD_FOR_TEN;
	if (r == 0)
		return 0;
	int firstN = 0;
	int secondN = 1;
	int tempHolder = 1;
	for (int i = 1; i < r; i++) {
		tempHolder = (firstN + secondN) % 10;
		firstN = secondN;
		secondN = tempHolder;
	}
	return secondN;
}
static int getLastDigit(long n) {
	if (n <= 1)
		return (int) n;
	int result = getFibNModM(n + 2);
	if (result == 0)
		return 9;
	else
		return result - 1;
}
static int getLastDigit(long m, long n) {
	if (m == n)
		return getFibNModM(n);
	else {
		int sumFn = getLastDigit(n);
		int sumFm;
		if (m <= 1)
			sumFm = 0;
		else
			sumFm = getLastDigit(m - 1);
		if (sumFn >= sumFm)
			return sumFn - sumFm;
		else
			return sumFn - sumFm + 10;
	}
}
//TEST(FibPartialSumLastDigit, Ten_200) {
//	ASSERT_EQ(getLastDigit(10, 200), 2);
//TEST(FibPartialSumLastDigit, One_2) {
//	ASSERT_EQ(getLastDigit(1, 2), 2);

int main() {
	long m, n;
	std::cin >> m;
	std::cin >> n;
	int c = getLastDigit(m, n);
	std::cout << c << '\n';
}