#include <iostream>
using namespace std;

int gs(int n, int p){
	int sum = 0;
	while(n/p > 0){
		n /= p;
		sum += n;
	}
	return sum;
}

int p1379(int s){
	int zhengge = s/10;
	int prod = (zhengge%2 == 0) ? 1 : 9;
	int mod = s%10;
	if(mod >= 3 && mod <= 6) prod *= 3;
	if(mod == 9) prod *= 9;
	return prod%10;
}

int fac1379(int n){
	int ans = 1;
	int pw2 = 1;
	while(pw2 <= n){
		int pw5 = 1;
		while(pw2 * pw5 <= n){
			int s = n / (pw2 * pw5);
			ans *= p1379(s);
			ans %= 10;
			pw5 *= 5;
		}
		pw2 *= 2;
	}
	return ans;
}

int ni(int n){
	if(n == 1 || n == 9) return n;
	if(n == 3) return 7;
	if(n == 7) return 3;
	return -1;
}

int pp2[4] = {6, 2, 4, 8};

int main() {
	int n, m;
	cin >> n >> m;
	int p2 = gs(n, 2) - gs(m, 2) - gs(n-m, 2);
	int p5 = gs(n, 5) - gs(m, 5) - gs(n-m, 5);
	int ans = fac1379(n) * ni(fac1379(m)) * ni(fac1379(n-m));
	ans %= 10;
	if(p2 > p5){
		ans *= pp2[(p2-p5)%4];
		ans %= 10;
	}
	if(p2 < p5){
		ans = 5;
	}
	cout << ans << endl;
	return 0;
}