can somebody help me figure out how to convert a string to a number? Let's say a user inputs "1-800-Flowers" I want python to display "1-800-3569377"

All I have so far is:

```
userInput = input("Please enter a phone number (e.g. 1-800-Flowers): ")
phoneNum = userInput.replace('-','')

```

That's really all I have. Any help would be much appreciated