@app.route("/upload", methods=["GET", "POST"])
def upload():
    if request.method == 'POST':
        if 'file' not in request.files:
            print(1)
            flash('No file part')
            return redirect(request.url)
        file = request.files['file']
        if file.filename == '':
            print(2)
            flash('No selected file')
            return redirect(request.url)
        if file and allowed_file(file.filename):
            print(3)
            filename = secure_filename(file.filename)
            session["id"] = filename
            file.save(os.path.join('UPLOAD', filename))
            return redirect(url_for('uploaded',
                                    filename=filename))

    return render_template('upload.html')