When writing programs, it is important to create ways for the user to interact with the program. In Python, we can use the `input()` function to get data from the user. ```python name = input("What is your name? ") print("Hello, " + name) ``` The `input()` function will wait for the user to type something in and then return that value. By default, the `input()` function will return a string. This is great, but you may need to convert the string to a number or another data type. You can convert one variable to another using any of the following functions, depending on the type of data you want: - `int()` - `float()` - `str()` - `bool()` For example, if you wanted to get the user's age as a number, you could use the `int()` function: ```python age_input = input("How old are you? ") age_as_number = int(age_input) time_til_retirement = 65 - age_as_number print("You will maybe be able to retire in " + str(time_til_retirement) + " years.") ``` Notice how we had to use `str()` to convert the number back into a string before we could combine it with the other text? Yeah, running your code will give you an error otherwise. You also may have noticed that we could have saved some code if we had written something like this: ```python age = int(input("How old are you? ")) ``` That would immediately convert the input into a number, but maybe would have been harder to understand when you read the code. ## Instructions Complete each of the following challenges using variables, operators, `input()`, and `print()`. **Challenge 1** > Create a program that takes in a First Name, Last Name, and Age, and prints out a greeting. > For example: > ```plaintext > Hello, Joe Smith, 32 > ``` **Challenge 2** > Create a program that takes in the sides `a` and `b` of a right triangle and prints out the length of the hypotenuse. > Remember the pythagorean theorem: > $ > a^2 + b^2 = c^2 > $ **Challenge 3** > You just got home from a trip around South America and have a few different currencies: > - Colombian Pesos > - Peruvian Soles > - Brazilian Reais > Write a program that takes in each currency, converts them to USD, and prints out the total value.