OFFSET
0,2
COMMENTS
PROG
(S/R) stvar $[N][N]:(0.. M-1) init $[][]:=0 asgn $[][]->{*} kill +[i in 0.. N-2](+[j in 0.. N-1](($[i][j]`-$[i+1][j]`>3)+($[i+1][j]`-$[i][j]`>3)+($[j][i]`-$[j][i+1]`>3)+($[j][i+1]`-$[j][i]`>3)))
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 31 2006
STATUS
approved