Two character strings may have many common substrings. Substrings are required to be con$-$

tiguous in the original string. For example, photograph and tomography have several common

substrings of length one $($i$.$e$.,$ single letters$),$ and common substrings ph$,$ to$,$ and ograph $($as well

as all the substrings of ograph$).$ The maximum common substring $($MCS$)$ length is $6.$

Let X $=$ x$1$x$2$ xm and Y $=$ y$1$y$2$ yn be two character strings