function solve() {
    let form = document.querySelector('form');
    let formButton = document.querySelector('form button');
    let sections = document.querySelectorAll('section');
    let total = 0;

    form.setAttribute('onsubmit', 'return false;');

    const regex = /[\d\.]+/gm;

    form.lastElementChild.addEventListener( "click", function (event) {
        let name = form.getElementsByTagName('input')[0].value.trim();
        let year = +form.getElementsByTagName('input')[1].value;
        let price = +form.getElementsByTagName('input')[2].value;

        if( name != '' && year > 0 && price > 0 ) {
            createBook(name, year, price);
        }
    });

    function remove(e) {
         e.target.parentNode.remove();
    }

    function totalProfit( price ) {
        total += +price;
        form.nextElementSibling.innerHTML = ` Total Store Profit: ${Number.parseFloat(total).toFixed(2)} BGN`;
    }

    function createBook( bookName, year, price ) {
        let section;
        let formatPrice = price;

        let divBook = document.createElement('div');
        divBook.className = 'book';

        let p = document.createElement('p');
        p.innerText = `${bookName} [${year}]`;

        let buttonBuy = document.createElement('button');
        let buttonMove = document.createElement('button');
        buttonMove.innerText = `Movie to old section`;

        divBook.appendChild( p );

        if( year > 2000 ) {
            section = sections[1];
            buttonBuy.innerText = `Buy it only for ${ Number.parseFloat(formatPrice).toFixed(2)} BGN`;
            divBook.appendChild( buttonBuy );
            divBook.appendChild( buttonMove );

        } else {
            section = sections[0];
            formatPrice *= .85;
            buttonBuy.innerText = `Buy it only for ${ Number.parseFloat(formatPrice).toFixed(2)} BGN`;
            divBook.appendChild( buttonBuy );
        }


        section.lastElementChild.appendChild( divBook );

        buttonBuy.addEventListener("click", buyBook );
        buttonMove.addEventListener("click", moveBook );

    }

    function buyBook(e) {
       totalProfit( e.target.innerText.match(regex)[0] );
        remove(e);
    }

    function moveBook(e) {

        let price = e.target.previousElementSibling.innerHTML.match(regex)[0] * 0.85;
        e.target.previousElementSibling.innerHTML = `Buy it only for ${ Number.parseFloat(price).toFixed(2)} BGN`;
        let divBook =  e.target.parentNode;
        e.target.remove();

        sections[0].appendChild( divBook);

    }

}