3m - 3 + mn - n = 3*(m - 1) + n*(m - 1) = (3 + n)*(m - 1) = (3+n)*0 = 0
3*1-3+1*(-1целая 11/19)+1целая 11/19=0
3m - 3 + mn - n = 3*(m - 1) + n*(m - 1) = (3 + n)*(m - 1) = (3+n)*0 = 0
3*1-3+1*(-1целая 11/19)+1целая 11/19=0