(rand2 > death) && (rand2 <=

   death + birth) && (rand3 < (m/(n + m))), (n = n) && (m =

   m + 1), (n = n) && (m = m)

];

If[(rand2 > death) && (rand2 <=
      death + birth) && (rand3 < (n/(n + m))), (n = n + 1) && (m =
       m), (n = n) && (m = m)
   ];

(rand2 < death) && (rand3 < (m/(n + m))), (n = n) && (m =

   m - 1), (n = n) && (m = m)

];

If[

   (rand2 < death) && (rand3 < (n/(n + m))), (n = n - 1) && (m =

      m), (n = n) && (m = m)

   ];

rand1 <= 1/2, (n = n + 1) && (m = m), (n = n) && (m = m + 1)

];