Write a Python program that reads a text file. The program should:

1. Convert all words to lowercase.

2. Store the words in a list.

3. Use a dictionary to count how many times each word appears.

4. Find and print the word(s) with the minimum frequency (i.e., words that occur least often).

Example of the text file words:

Apple banana apple ORANGE Banana orange.

ORANGE apple BANANA apple.

Example of code execution:

Enter the filename: text1.txt

Words with the minimum frequency:

orange.

apple.