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:  0 0 0 0 0 0 0 0 3 7 4 9 6 2 3 9 2 2 3 4
Output: 3 4 0 0 0 0 0 0 0 0 3 7 4 9 6 2 3 9 2 2

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

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

Below is a test input grid. Predict the corresponding output grid by applying the rule you found.
Input:
7 2 9 3 8 4 3 3 8 0 0 0 5 7 1 1 1 2 1 6
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