250 RUB reward can be claimed by anyone who completes this task.

The link is two subsequences, we can cache the relationship between each array of subsequence's elements and its address. So if need to convert the address to array of elements second time we can do it faster, because of cached arrays. This can have a significant impact on the speed of reading of data from Links storage.

We also can store a file with read sequence for a cache duration (1 sec or greater). This file should be created each time the sequence that does not have such file is read.