Question $3$: Write a program that prompts the user to input the size of rows and col umns of an nxm matrix. Then calculate the sum of the diagonal of the matrix.

Sample Run:

Enter a value for the row: $4$

Enter a value for the column: $4$

The matrix:

$1234$

$1234$

$1234$

$1234$

The sum of the diagonal: $10$