Count Pentagonals in a Range
How many pentagonal numbers (1, 5, 12, 22, ...) lie in [L, R]?
Input: one line with two integers L and R.
Output: the count of such numbers in the range.
Constraints:
- 1 ≤ L ≤ R ≤ 1018
Sample Tests
Input 1
1 20
Output 1
3
Input 2
5 5
Output 2
1
Discussion (opens after you solve — no spoilers before)
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