#define ll long long

#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <math.h>

using namespace std;

int main() {
    int n, k;
    cin >> n >> k;
    if (n >= 10) {
        switch (k) {
            case 1:
                cout << 4;
                break;
            case 2:
                cout << 8;
                break;
            case 3:
                cout << 5;
                break;
        }
    } else {
        ll arr[10];
        for (int i = 0; i <= n; i++) {
            if (i == 0) {
                arr[i] = 1;
            } else {
                arr[i] = arr[i - 1] * i;
            }
        }

        for (int i = 0; i < k; i++) {
            ll sum = 0;
            for (int j = 0; j <= n; j++) {
                sum += arr[j];
            }

            if (i == k - 1) {
                while (sum != 0) {
                    if (sum % 10 != 0) {
                        cout << sum % 10;
                        break;
                    }
                    sum /= 10;
                }
            }

            for (int j = 0; j <= n; j++) {
                arr[j] *= arr[j];
            }
        }
    }

    return 0;
}