class List {
    arr = [];

    add(element) {
        this.arr.push(element)
    }

    remove(index) {
        if (this.arr.indexOf(index) !== -1) {
            throw new Error(`Index doesn't exist`);
        } else {
            this.arr.splice(index, 1);
        }
    }

    get(index) {
        if (this.arr.indexOf(index) !== -1) {
            throw new Error(`Index doesn't exist`);
        } else {
            return this.arr[index];
        }
    }

    size() {
        return this.arr.length;
    }
}