Work with files

The given text of the program in any algorithmic language and a dictionary of reserved words of this language. Convert the text by writing all the reserved ones
words in capital letters (upper case), and other constructions (identifiers, etc.) - small.
Please help to write this code.

If you want help, you need to make an initial effort.

Show us where you can get to, and where you're actually stuck.
Then we can tell you what you need to know to move forward.