function solve() {
    let priceMap = {
        "js-fundamentals": 170,
        "js-advanced": 180,
        "js-applications": 190,
        "js-web": 490,
    };

    let listCourses = document.querySelector("#myCourses > div.courseBody > ul");
    document.querySelector("#availableCourses > div.courseFoot > button").addEventListener("click", () => {
            let type = "";
            let selected = [];
            Array
                .from(document.querySelectorAll("input"))
                .filter(el => el.checked === true)
                .forEach(el =>
                    el.value.includes("js") ? selected.push(el.value) : type = el.value
                );

            let sum = getPrice(selected);
            let price = Math.floor(sum);

            let priceForm = document.querySelector("#myCourses > div.courseFoot > p");
            let curPrice = Number(priceForm.innerHTML.split(" ")[1]);
            priceForm.innerHTML = `Cost: ${curPrice + price}.00 BGN`;

            function getPrices(type) {
                if (type === "online") {
                    priceMap["js-fundamentals"] = priceMap["js-fundamentals"] * 0.94;
                    priceMap["js-advanced"] = priceMap["js-advanced"] * 0.94;
                    priceMap["js-applications"] = priceMap["js-applications"] * 0.94;
                    priceMap["js-web"] = priceMap["js-web"] * 0.94;
                }
            }

            function transformName(courseName) {
                let tokens = courseName.split("-");
                let fPart = tokens[0].toUpperCase();
                let name = fPart + "-" + String.fromCharCode(tokens[1].charCodeAt(0) - 32);
                for (let i = 1; i < tokens[1].split("").length; i++) {
                    name += tokens[1].charAt(i);
                }
                return name;
            }

            function addToCourses(courseName) {
                if (courseName !== "HTML and CSS") {
                    courseName = transformName(courseName);
                }
                let applications = document.createElement("li");
                applications.innerHTML = courseName;
                listCourses.appendChild(applications);
            }

            function getPrice(selected) {
                getPrices(type);
                let arrCopy = selected.slice(0, selected.length);
                let price = 0;
                if (selected.indexOf("js-fundamentals") !== -1 && selected.indexOf("js-advanced") !== -1) {
                    price += priceMap[selected.shift()] + (priceMap[selected.shift()] * 0.90);
                    if (selected.indexOf("js-applications") !== -1) {
                        price += priceMap[selected.shift()];
                        price *= 0.94;
                    }
                    if (selected.length === 1) {
                        price += priceMap[selected.shift()];
                        arrCopy.push('HTML and CSS');
                    }
                }
                while (selected.length > 0) {
                    price += priceMap[selected.shift()];
                }
                arrCopy.forEach(el => addToCourses(el));
                return price;
            }
        }
    );
}