from flask import Flask, escape, request, make_response

app = Flask(__name__)

@app.route('/')
def page1():

    res = '''
    <form action="/page2">
        Enter your first number:
        <input type="text" name="first">
        <input type="submit" value="Submit">
    </form>
    '''

    return res

@app.route('/page2')
def page2():
    first_number = request.args.get("first")
    
    res = '''
    <form action="/page3">
        Enter your second number:
        <input type="text" name="second">
        <input type="submit" value="Submit">
    </form>
    '''

    return res

@app.route('/page3')
def page3():
    first_number = request.args.get("first")
    second_number = request.args.get('second')

    # statement will fail if first_number and second_number are not 
    # valid integers
    return "your number is: " + str(int(first_number) + int(second_number))


if __name__ == '__main__':
    app.run(use_reloader=True, debug=True)