The next step is to read in the number of particles \( N \) and the fixed total \( M \) (or, actually, \( 2 \times M \)). For this project we assume only a single species of particles, say neutrons, although this can be relaxed. Note: Although it is often a good idea to try to write a more general code, given the short time alloted we would suggest you keep your ambition in check, at least in the initial phases of the project.

You should probably write an error trap to make sure \( N \) and \( M \) are congruent; if \( N \) is even, then \( 2 \times M \) should be even, and if \( N \) is odd then \( 2\times M \) should be odd.