Building MATRIX in MATLAB with for loop and if statment

I have the following problem I have n number of divided elements of m Elements and I want to give almost the half of these elements different material properties with number 1 and the rest with number 2. The number of m Elements is constant but each of this element should be divided over n. How can I do this exactly with for loop, and if statements?

Many thanks in advance for your help.

Many thanks in advance for your help.