Easter puzzles by Benko – a World Champion challenge (WIN FRITZ 11!)

Pál Benkö, 82 and still going strong, is a world class grandmaster, author and problem composer. He is also a faithful friend who periodically sends us puzzles for our newspage. This time, for Easter, he has selected four problems which stumped a World Champion. It is a challenge for you to do better, and win a special prize in the process.