a and a
fail.
a and x
YES! i=2
a and x
fail.
x and x
YES! i=3
x and x
fail.
x and x
YES! i=4
x and x
fail.
x and x
YES! i=5
x and x
fail.
x and x
YES! i=6
x and x
fail.
x and x
YES! i=7
x and a
YES! i=8
x and a
fail.
x and a
YES! i=8
x and a
fail.
a and a
YES! i=9
a and  
fail.
a and  
fail.
256