<|im_start|>system
You are a helpful assistant. You first think about the reasoning process in the mind and then provides the user with the answer.<|im_end|>
<|im_start|>user
Find the common rule that maps an input grid to an output grid, given the examples below.

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

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

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

Below is a test input grid. Predict the corresponding output grid by applying the rule you found.
Input:
6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8 7 9 4 4 7 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>.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>
user