Problem

Given two lists of transaction IDs, list1 and list2, return a list of transaction IDs that exist in list1 but not in list2.

Examples

Example 1:

Input: list1 = ['A123', 'B456', 'C789'], list2 = ['B456', 'D012']
Output: ['A123', 'C789']

Example 2:

Input: list1 = ['X001', 'X002', 'X003'], list2 = ['X002']
Output: ['X001', 'X003']

Constraints

• 1 <= list1.length, list2.length <= 10^5
• Transaction IDs are strings with a maximum length of 100 characters.