Problem E. Data Center Drama
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Statement clarification. The task is to combine all cables attached to each computer in groups consisting of exactly two cables. Each group should contain two outgoing cables or two ingoing cables, but not an outgoing and ingoing. In particular, each cable should belong to 2 groups, one for each computer it connects. It is not allowed to combine a loop in a group with itself because it is both an outgoing and ingoing cable. The resulting scheme should not be neccessarily connected in any sence (look on the first sample test for the clarification). The image for the second test case is wrong, it will be fixed.

Problem B. Error Correct System
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Both strings contain only lowercase Latin letters. This will be added shortly.