<div class="user_solution">1. hf3! <br />1... kc4 2. kb6 kd5 3. he3 kd6 4. bc5#, <br />2... kb3 3. hd2 ka4 4. bd7#, <br />3... ka2 4. be6#.<br /><br />b): <br />1. kb6? <br />1...kd6 2. bf6 kd5 3. he3 kd6 4. he8#, 1... kc4!<br />1. bc3? <br />1... kc5 2. bd3 kd5 3. he3 (hb4) kc5 4. he6#, 1... kc4!<br /> 1. he6! <br />1... kc4 2.hc5 kb5 (kd5? 3. be6#) 3. bd3 ka5 4. bc3#.<br /><br /></div>