0031. Primesets
| Input file name: | primeset.in |
| Output file name: | primeset.out |
| Time limit: | 20 s |
| Memory limit: | 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.
Examples:
| primeset.in | primeset.out |
|---|---|
| 1 2 | 4 |
Source: Petrozavodsk training camp, Summer 2002. Startup contest
Author: Andrew Lopatin, Nick Durov
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