Find the number of n*m 01 matrices that meet the following conditions:
(1) There is exactly one 1 in the i-th row and columns 1 to li.
(2) There is exactly one 1 in the ri~m column of the i-th ro
Find the number of n*m 01 matrices that meet the following conditions:
(1) There is exactly one 1 in the i-th row and columns 1 to li.
(2) There is exactly one 1 in the ri~m column of the i-th ro