Serial Compatibility

Two hardware serial numbers are 'compatible' if they have the same length and differ by exactly one character at the same position. Given a list of N unique serial numbers, find the total number of compatible pairs. Input Format: - Line 1: Integer N. - Next N lines: Unique serial number strings (all same length). Output Format: - A single integer representing the number of compatible pairs. Example: Input: 3 abc abd acc Output: 2 (Explanation: (abc, abd) differ at index 2. (abc, acc) differ at index 1.)