Solution 1

 white to move and win
At first glance,white seems to win easily by Kc3-Kb4-Kxa4. But after 1.Kc3,1...a3! draws. e.g. 2.bxa3 Ke6 3.Kc4 Kd6 4.Kb5 Kc7 draw 2.b3 Ke5 3.Kb4?? a2 black wins 2.b4 Ke6 3.Kb3 Kd6 4.Kxa3 Kc6 5.Ka4 Kb6 draw 1.Kb1! It's not the shortest route to a4,but this position doesn't require the shortest one. 1...Ke5 2.Ka2 Kd4 3.Ka3 Kc5 4.Kxa4 wins just in time. 2...a3 3.b3 3.b4 fails because the Pawn would be advanced too far. 3...Ke5 Ka2 4.Kxa3 Kc5 5.Ka4 Kb6 6.Kb4 and wins. (F.Dedrle 1921) REFERENCE : Practical Chess Endings(Paul Keres) Basic Chess Endings(Reuben Fine)