function getNumberOfSticks(items) {
    const reference = [
        { lvl: "A0", barlvl: 1 },
        { lvl: "A1", barlvl: 1 },
        { lvl: "A2", barlvl: 2 },
        { lvl: "A2+", barlvl: 2 },
        { lvl: "B1", barlvl: 3 },
        { lvl: "B1+", barlvl: 4 },
        { lvl: "B2", barlvl: 5 },
        { lvl: "B2+", barlvl: 5 },
        { lvl: "C1", barlvl: 6 },
        { lvl: "C1+", barlvl: 6 },
        { lvl: "C2", barlvl: 6 },
    ];
    const MAX_LVL = 6;
    const result = [];
    const sticks = [];
    items.forEach((item) => {
        reference.find((reference) => {
        if (
            item === reference.lvl &&
            sticks.length <= MAX_LVL &&
            sticks.indexOf(reference.barlvl) == -1 &&
            result.indexOf(reference.lvl) == -1
        ) {
            result.push(item);
            sticks.push(reference.barlvl);
        }
        });
    });
    return Math.max.apply(Math, sticks);
    }
    const sticks = getNumberOfSticks([
    "A0",
    "A0",
    "A2",
    "A3",
    "B1+",
    "A2",
    "A1",
    "K5",
    "B2",
    ]);
    console.log(sticks);