(;SZ[4]AB[da]AB[db]AB[ab]AB[aa]AB[bd]AB[cd]AW[ad]AW[ac]AW[bc]AW[dc]AW[dd]AP[goproblems]
(;B[cb];W[bb]
(;B[cc];W[ba]C[Wrong! This is a seki!])
(;B[ba];W[cc]))
(;B[cc];W[bb]
(;B[cb];W[ba]C[Wrong! This is a seki!])
(;B[ba];W[ca]
(;B[cb];W[ba]
(;B[ab]C[Well done!RIGHT])
(;B[aa]C[Well done!RIGHT]))
(;B[ba]C[];W[aa];B[cb];W[dc];B[ba]C[];W[bc];B[ab]C[Well done!RIGHT])))
(;B[bb];W[cc];B[cb];W[ba]LB[aa:D]LB[ab:D]LB[da:D]LB[db:D]LB[cb:D]LB[bb:D]C[Black is dead! (marked D]))