db ={}
def newuser():
    prompt = \'login desired:\'
    while True:
        name = raw_input(prompt)
        if db.has_key(name):
            prompt = \'name taken,try another.\'
            continue
        else:
            break
    pwd = raw_input(\'passwd:\')
    db[name] = pwd
def olduser():
    name = raw_input(\'login\')
    pwd = raw_input(\'passwd\')
    passwd = db.get(name)
    i = 0
    while i <3:
        if passwd == pwd:
            print \'welcome back\',name
            break
        else:
            print \'passwd wrong ,try again.\'
            i = i + 1
def showmenu():
    prompt = \'\'\'
    (N)ew User
    (E)xiting User Login
    (Q)quit
    enter choice
    \'\'\'
    done = False
    while not done :
        chose = False
        while not chose:
            try:
                choice = raw_input(prompt).strip()[0].lower()
            except (EOFError,KeyboardInterrupt):
                choice = \'q\'
            print \'\nYou picked"[%s]\' % choice
            if choice not in \'neq\':
                print \'invalid option, try again.\'
            elif choice == \'n\':
                newuser()
                chosen = True
                done = True
            elif choice == \'e\':
                olduser()
                chosen = True
                done = True
            else :
                break
if __name__ == \'__main__\':
    showmenu()