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A school wants to split students into two photo groups.
The height of the -th student is .
The two groups must be non-empty. A group is called good if the difference between the tallest and the shortest student in that group is at most .
Determine whether it is possible to split all students into two good groups.
One possible split is to put the students with heights and in one group, and the students with heights , , and in the other group.
Both groups are good.
The students with heights , , and can form a good group.
However, the remaining heights and differ by more than .
No split makes both groups good.
One group can contain the two students with height , and the other group can contain the two students with height .
In both groups, the tallest and shortest students have the same height, so the difference is .