Double double ( XQ Puzzle160707 )

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A composed position: How does Red win quickly ? 

FEN : 2bakN3/4aR3/4b4/1C1R5/6n2/9/C3c4/2n1B3c/4Ar3/2B1KA3 w - - 0 1

Highlight the space below for solution: 

1. R4=5 K5+1   2. R6+2 K5-1    3. R6+1 K5=4

4. C9+6 B3+1   5. C8+3 1-0