x1 = Mb
x2 = Bc
x3 = Bcp
x4 = Bn
x5 = Cc
x6 = Mc
x7 = Ccp
x8 = Mp
x9 = Pc
x10 = Pcp
x11 = PCc
x12 = PCcp
x13 = PCn
x14 = Bnp
x15 = PCnp
x16 = In
x17 = Mr
x18 = Rc
x19 = Rn