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≤ a_i≤ 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.

Examples:

primeset.in	primeset.out
1 2	4

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

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