Longest Substring with At Most Two Distinct Characters

Given a string s, find the longest substring that contains at most two distinct characters. If there are multiple substrings with the maximum length, return the one that appears first. Additionally, your program should print the length of the longest substring on the first line, followed by the substring itself on the second line.

Note: You need to read the input from standard input (stdin) and print the output to standard output (stdout).

For example:

Input:  abcbbbbcccbdddadacb
Output:
10
bcbbbbcccb

inputFormat

The input consists of a single line containing the string s. The string may be empty.

outputFormat

The output consists of two lines. The first line is an integer representing the length of the longest substring that contains at most two distinct characters. The second line contains the substring itself.

## sample

abcbbbbcccbdddadacb

10
bcbbbbcccb

</p>