How do you find an 'M' by 'M' submatrix in the center of an input 'N' by 'N' matrix?

How do I write a function in Matlab to output the M x M submatrix at the center of an N x N input matrix? The function should have two input arguments—the N x N input matrix (2D array) and the size of the square submatrix, M, to be extracted from the input matrix. The sole output should be the M x M submatrix at the center of the input matrix. The function should use for loops to extract the submatrix and not use colon notation or any built-in functions for this part of the code. The function should work for any square input matrix where N ≥ 3. If N is even, M should be even. If N is odd, M should be odd.