Найти сумму максимальных элементов каждого столбца двумерного массива — QBasic(Бейсик)

INPUT "vvedite kol-vo strok ", m
INPUT "vvedite kol-vo stolbcov ", n
DIM a(m, n)
RANDOMIZE TIMER
FOR i = 1 TO m
    FOR j = 1 TO n
        a(i, j) = INT(RND * 10)
    NEXT
NEXT
PRINT "matrica"
FOR i = 1 TO m
    FOR j = 1 TO n
        PRINT a(i, j);
    NEXT
    PRINT
NEXT
FOR j = 1 TO n
    max = a(1, j)
    FOR i = 1 TO m
        IF a(i, j) > max THEN max = a(i, j)
    NEXT
    PRINT "stolbec"; j; "max="; max
    s = s + max
NEXT
PRINT "summa max elementov stolbcov="; s