Найти произведение положительных элементов массива A(N,M) — Basic(Бейсик)

INPUT"vvedite kolichestvo strok N ",n
INPUT"vvedite kolichestvo stolbcov M ",m
DIM a(n,m)
FOR i=1 TO n
FOR j=1 TO m
INPUT "vvedite element ",a(i,j)
NEXT
NEXT
FOR i=1 TO n
FOR j=1 TO m
PRINT a(i,j);
NEXT
PRINT
NEXT
p=1
FOR i=1 TO n
FOR j=1 TO m
IF a(i,j)>0 THEN p=p*a(i,j)
NEXT
PRINT
NEXT
PRINT"proizvedenie=";p