> Make up a system of linear equations with coefficients in field F2
> and solve it!

I solved it but I still get WA. I find the solution, and go backward.
But there's situation where I can't solve simply equation a * x = b,
and have only one solution for it, ie 0 * x = 0, x can be either 1 or
0, and next equations depends on this one, so I have to find the
shortest one. I use BF to find them. Guess that x is 1 and try to
solve it, and after that I guess that x is 0.

dejan