import java.util.*;

public class Solution {

    public static void main(String[] args) {
        (new Test()).test();
    }

    static class TetrominoBag {

        private LinkedList<Character> tetrominos = new LinkedList<>();
        private Random randomizer;

        public TetrominoBag() {
            this.randomizer = new Random();
        }

        public TetrominoBag(long randomSeed) {
            this.randomizer = new Random(randomSeed);
        }

        private void refillBag() {
            assert(tetrominos.isEmpty());

            tetrominos.add('I');
            tetrominos.add('T');
            tetrominos.add('S');
            tetrominos.add('Z');
            tetrominos.add('O');
            tetrominos.add('L');
            tetrominos.add('J');
            Collections.shuffle(tetrominos, randomizer);
        }

        public Character nextTetromino() {
            if (tetrominos.isEmpty()) {
                refillBag();
            }

            return tetrominos.poll();
        }

    }

    static class Test {

        private TetrominoBag bag;

        public void test() {
            bag = new TetrominoBag(1);
            testTetromino('Z');
            testTetromino('I');
            testTetromino('L');
            testTetromino('T');
            testTetromino('S');
            testTetromino('J');
            testTetromino('O');

            testTetromino('L');
        }

        private void testTetromino(char expected) {
            final Character actual = bag.nextTetromino();
            if (actual == expected) {
                System.out.println("OK    Tetromino " + actual + " was expected.");
            } else {
                System.out.println("FAIL  Expected: " + expected + ", Actual: " + actual);
            }
        }

    }

}