Assuming the user will give a text input later, let me outline the steps. For each word in the text, check if it's a proper noun. How to identify proper nouns? They are capitalized unless in the middle of a sentence. But that's not always reliable. Maybe relying on a proper noun list or NER (Named Entity Recognition) would be better. However, since I can't use external libraries, I'll have to make an educated guess based on capitalization. But this approach has limitations.
Example output format: "word1"optA "word2"optY ...
Potential issues: Proper noun detection accuracy, generating relevant synonyms, handling words with multiple meanings. But given the constraints, the best approach is to proceed with the best-effort basis, using common knowledge to identify proper nouns and generate plausible alternatives.
