0031. Primesets

Имя входного файла: primeset.in
Имя выходного файла: primeset.out
Ограничение по времени: 20 s
Ограничение по памяти: 64 megabytes

Your task is to count all groups of three natural numbers a1, a2, a3 in range A≤ ai≤ B which have the property that any selected two of them are relatively prime. For example, when A=1 and B=2 there are only four groups: (1, 1, 1), (1, 1, 2), (1, 2, 1), (2, 1, 1).

Input file

The input file consists of two integer numbers A and B, where 1≤ A≤ B ≤ 30000 and B-A≤ 1700.

Output file

You are to output the number of such groups.


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Источник: Petrozavodsk training camp, Summer 2002. Startup contest
Автор: Andrew Lopatin, Nick Durov

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