Subtraction Matrix

Enter numbers and make the difference shown.

[Rule]
1. You can use numbers from 1 to 16.
2. You cannot use the same number more than once.

[End of game]
If all the numbers are entered correctly, it will end.
You can end the game even in the middle of the game by pressing the end button.

[Record]
If the game end time is earlier than the recorded time, that time will be recorded.
The recorded time can be erased by pressing and holding it.

[Hint]
Let's start from the place with the fewest subtraction combinations.