How to change the values in a matrix

I have created a for loop to create a matrix,

n = input("Enter number of rows for matrix ");
m = input("Enter number of columns for matrix ");
a = zeros(n:m);
x = n*m;
for i = 1:x
    if i == 1
        a(i) = 1;
    elseif i > 1 && i < n
        a(i) = 8;
    elseif i == n
        a(i) = 7;
    elseif i == x
        a(i) = 5;
    elseif i == (x-(n-1))
        a(i) = 3;
    elseif i > (x-(n-1)) && i < x
        a(i) = 4;
    elseif i == x
        a(i) = 5;
    
    else
        a(i) = 9;
    end
end

The matrix created is

Enter number of rows for matrix 5
Enter number of columns for matrix 5
     1     9     9     9     3
     8     9     9     9     4
     8     9     9     9     4
     8     9     9     9     4
     7     9     9     9     5

Now I wish to change the values of the first row to 2's excluding the first and last value in the row. If any body is able to help it will be greatly appriciated!

Thank you

Answer 1

[Star Strider]

One approach:

Before = [  1     9     9     9     3
            8     9     9     9     4
            8     9     9     9     4
            8     9     9     9     4
            7     9     9     9     5]

After = Before;
After(1,2:end-1) = ones(size(Before(1,2:end-1)))*2

producing:

After =
     1     2     2     2     3
     8     9     9     9     4
     8     9     9     9     4
     8     9     9     9     4
     7     9     9     9     5