3 Knights CheckMate

CheckMate in 7 move whit 3 knight in a good position but this position comes form one of the worse position that took 49 move to force black into checkmate.                                                                                                         

 Note that the basic concept is the same ther only two ways two checkmate whit 3 knight. Thers this one and ther the other one witch is to pill up 3 knight in one line whit the black king in a coner and the whit king 1 square form the black king.