Daily Chess Improvement: MUST MUST MUST KNOW Chess Endgame!

This is a mirror image of a famous Reti Chess Endgame

Wouldn't it be a pity if you fight so hard throughout the entire chess game only to lose because your endgame technique is deficient?

It is white to move in the chess position above. Is this a draw or loss for white? How should white proceed?

No. 1-1
  1. Kb7! a4, 2. Kc6 Kg6, 3. Kd5! (threatening Ke6) Kxf6, 4. Kc4 =