def existingUser():
    for i in range(5):
        existingUsername = input("What is your user name?")
        if existingUsername in open('logins.txt').read():
            with open("logins.txt", "r") as myFile:
                for num, line in enumerate(myFile, 1):
                    if existingUsername in line:
                        passwordLine = num + 1
                        passwordAttempt = input("What is your password?")
                        loginsList=myFile.readlines()
                        passwordText = loginsList[passwordLine]
                        if passwordText == passwordAttempt:
                            print("That is correct")
                            quizSelection()
                            break
                        else:
                            print("That doesn't seem to match. Please try again")

def existingUser(max_tries=3):
    with open('logins.txt') as fp:
        lines = [line.strip() for line in fp.readlines()]
    logins = dict(zip(lines[::2], lines[1::2]))

    for n in range(max_tries):
        username = input("What is your user name? ")
        password = input("What is you password? ")
        if logins.get(username) == password:
            print("That is correct")
            return username
        else:
            print("try again")
    print("Too many tries")
    return False

if existingUser():
    quizSelection()