Special Number Finding from a 2-D Matrix

Two friends, Bob and John meet after a long time and they start playing one of their favourite games. Bob has been given a matrix of size $m*n$, where $m$ presents the number of rows starting with index 0 and $n$ refers to the number of columns starting with index 0. This matrix contains distinct positive integers as elements. Now, the task for John is to identify a special number of positional e