A conversation between User and Assistant. The user asks a question, and the Assistant solves it. The assistant first thinks about the reasoning process in the mind and then provides the user with the answer.
User: Find the common rule that maps an input grid to an output grid, given the examples below.

Example 1:
Input:  4 8 2 7 1 0 0 0 0 0 0 0 0 3 9 7 5 6 7 1 5 7 3 2 8 8 9
Output: 2 7 1 0 0 0 0 0 0 0 0 3 9 7 5 6 7 1 5 7 3 2 8 8 9 4 8

Example 2:
Input:  6 2 6 2 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 2 5 3 6 6 2 9 8
Output: 6 2 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 2 5 3 6 6 2 9 8 6 2

Example 3:
Input:  2 7 1 8 9 5 4 8 8 1 4 3 8 1 9 6 3 5 5 1 5 3 6 2 7 2 9
Output: 1 8 9 5 4 8 8 1 4 3 8 1 9 6 3 5 5 1 5 3 6 2 7 2 9 2 7

Below is a test input grid. Predict the corresponding output grid by applying the rule you found.
Input:
2 7 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 5 5 8 4
Show your work in <think> </think> tags, and return the answer in <answer> </answer> tags with space between each number. For example <answer> 1 3 5 7 </answer>.
Assistant: Let me solve this step by step.
<think>
user