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:  3 4 9 4 4 0 0 0 0 0 0 0 0 0 0 8 2 5 5 7 4 5
Output: 9 4 4 0 0 0 0 0 0 0 0 0 0 8 2 5 5 7 4 5 3 4

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

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

Below is a test input grid. Predict the corresponding output grid by applying the rule you found.
Input:
9 1 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
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