Unique Email Verification

You are developing a system to validate unique email addresses. Given a list of email addresses, you need to determine if there are any duplicates based on the local part of the email before the '@' symbol. An email is considered a duplicate if another email exists in the list with the same local part (case-insensitive). Your program should print the duplicate email local part if duplicates exist; otherwise, print 'All emails are unique'. Input: The first line contains an integer N (1 <= N <= 10000), the number of email addresses. The following N lines each contain an email address. Output: Print the duplicate email local part if duplicates exist, otherwise print 'All emails are unique'. Example: Input: 3 test.email+alex@gmail.com test.email@gmail.com testemail@gmail.com Output: test.email