121 - P2 then P1
101 - P1 then P2
100 - P1 gets x^2 to be 100. Then P2 sets x after which P1 sets x to be 100.

110 cannot be done since x^2 will not be interleaved with P2 which means the value of x will be the same meaning it is either 100 or 121.
11 cannot be done since once P2 starts, P1 cannot finish until P2 is done.

adams