static int cells = Math.min(((playerOnline() - 2) / 9) * 9 + 9, 54);

    private static Integer playerOnline(){
        int plson = 0;
        for(Player pls : Bukkit.getOnlinePlayers()){
            if(pls.getGameMode() == GameMode.SURVIVAL){
                plson ++;
            }
        }
        return plson;
    }

    public static void openMenu(Player player){
        Inventory inv = Bukkit.createInventory(null, cells, "§cJoueurs en vie");

        for(Player plon : HungerGames.players){
            int slot = 0;
            for(int i = 0; i < cells; i++){
                ItemStack head =  new ItemStack(Material.SKULL_ITEM, 1, (short) 3);
                SkullMeta meta = (SkullMeta) head.getItemMeta();
                meta.setOwner(plon.getName());
                meta.setDisplayName(plon.getName());
                head.setItemMeta(meta);
                inv.setItem(slot, head);
                slot++;
            }
        }
        player.openInventory(inv);
    }