Найти среднее арифметическое положительных элементов массива A(N,M) — QBasic(Бейсик)

INPUT "vvedite kolichestvo strok N ", n
INPUT "vvedite kolichestvo stolbcov M ", m
RANDOMIZE TIMER
DIM a(n, m)
FOR i = 1 TO n
    FOR j = 1 TO m
        a(i, j) = INT(RND * 20) - 10
    NEXT
NEXT
PRINT "matrica "
FOR i = 1 TO n
    FOR j = 1 TO m
        PRINT a(i, j);
    NEXT
    PRINT
NEXT
FOR i = 1 TO n
    FOR j = 1 TO m
        IF a(i, j) > 0 THEN s = s + a(i, j): k = k + 1
    NEXT
NEXT
PRINT "srednee="; s / k