while(arr.length < pictures.length){
                                        var randomenumber = Math.floor((Math.random()* 16));
                                        if(arr.indexOf(randomenumber) > -1){
                                            continue;
                                         }
                                         arr[arr.length] = randomenumber;
                                    }
                                    //cheat sheet
                                    for(var i = 0; i < arr.length ; i++){

                                        document.write(arr[i]);
                                        document.write("</br>");

                                    }