Statement

George has recently enrolled in a Kabbalah seminar, where a few cultured savants debate on the concealed wisdom of the Bible. In particular, their favorite hobby is searching the Bible for long sequences of equal letters. Firstly, the seminar master selects an N × M rectangle of characters C_i,j from the holy scriptures. Afterwards, the adepts search in all directions (horizontal, vertical and diagonal) for contiguous sequences of equal letters and the longer the sequence found, the greater the glory for the finder. Help George prove his wisdom by finding the longest sequence of equal letters!