В матрице найти максимальный и минимальный элементы

INPUT "vvedite kol-vo strok ", n
INPUT "vvedite kol-vo stolbcov ", m
DIM a(n, m)
RANDOMIZE TIMER
FOR i = 1 TO n
FOR j = 1 TO m
a(i, j) = INT(RND * 8) + 1
NEXT
NEXT
PRINT "massiv"
FOR i = 1 TO n
FOR j = 1 TO m
PRINT a(i, j);
NEXT
PRINT
NEXT
min = a(1, 1)
xmin = 1
ymin = 1
max = a(1, 1)
xmax = 1
ymax = 1
FOR i = 1 TO n
FOR j = 1 TO m
IF a(i, j) < min THEN min = a(i, j): xmin = i: ymin = j
IF a(i, j) > max THEN max = a(i, j): xmax = i: ymax = j
NEXT
NEXT
OPEN "output.txt" FOR OUTPUT AS #1
PRINT #1, "min= a("; xmin; ","; ymin; ")="; min
PRINT #1, "max= a("; xmax; ","; ymax; ")="; max
IF xmin > xmax THEN SWAP xmin, xmax
IF ymin > ymax THEN SWAP ymin, ymax
p = 1
FOR i = 1 TO n
FOR j = 1 TO m
IF i >= xmin AND i <= xmax AND j >= ymin AND j <= ymax THEN p = p * a(i, j) ELSE s = s + a(i, j)
NEXT
NEXT
PRINT #1, "proizvedenie="; p
PRINT #1, "summa="; s
CLOSE

INPUT "vvedite razmer N ", n
x = 0
y = 1
num = 1
dlina = n
shag = 1
DO WHILE dlina <> 0
 i = 0
DO WHILE i <> dlina
    x = x + shag
    a(y, x) = num
    num = num + 1
    i = i + 1
  LOOP
 i = 0
 dlina = dlina - 1
DO WHILE i <> dlina
  y = y + shag
  a(y, x) = num
  num = num + 1
  i = i + 1
LOOP
  shag = shag * (-1)
LOOP
OPEN "output.txt" FOR OUTPUT AS #1
FOR i = 1 TO n
  FOR j = 1 TO n
   PRINT #1, a(i, j);
  NEXT
 PRINT #1, ""
 NEXT
CLOSE