Problem

Source: JBMO 2009 Shortlist C3

Tags: JBMO, combinatorics



a) In how many ways can we read the word SARAJEVO from the table below, if it is allowed to jump from cell to an adjacent cell (by vertex or a side) cell? b) After the letter in one cell was deleted, only $525$ ways to read the word SARAJEVO remained. Find all possible positions of that cell.


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