Problem 42695. Replace secondary diagonal elements of a square array

Replace all the secondary diagonal elements of the square array A with the number n

Example:

 A = [1 2 3
      4 5 6
      7 8 9]
 n=0

 Output = [1 2 0
           4 0 6
           0 8 9]

Example 2

 A = 1;
 n = 10;

 Output = 10