8/K2P3p/6P1/5P2/4p3/5P2/3r1P2/k7 w - - 0 1
Well done, Alena. That last section is extremely difficult to get through because of the several "only winning moves" white has to find, in particular 7.Ke4 and the need to manuever to keep the black king off the d-file so that the rook can't safely skewer the king and new queen from in between them.
A more testing defense for black is 6......Rd7+, and is the main line of the puzzle- it forces white to play more accurately.
It's a winning position for white.
This is very good, Alena. Now consider V-1 immediately above. There are two things you need to do now- first lets take you actual line 1.Kb6 Rxd7
5.f4 Here, you had black putting the rook behind the f-pawns at f2 on move 5, now consider what white must do if black puts the rook on h4 instead to attack the backward f-pawn that way. Also, can you see why it had to be 5.f4? In short, 5.f4 forces black to capture at f4 thus gaining a critical tempo because it comes under attack. Finally, you need to tie up one very major loose end in this line, and that is where black plays 4......Kb2!- a much more tenacious defense than 4.....Rh2 is. That line after 4.....Kb2 is the heart and beauty of this puzzle.