Given the available moves based on the current board state in FEN notation, think carefully about which move would be best, then make that move. Be sure to note your color indicated in the FEN notation before deciding.
## Available Moves
b1a1
b1h1
b1g1
b1f1
b1e1
b1d1
b1c1
b1b5
b1b4
b1b3
b1b2
f2e1
f2a7
f2b6
f2c5
f2d4
f2e3
f2g1
f2h4
f2g3
g2g3
g2g1
g2f1
c3c4
a4b5
f5f6

## Board State Fen
7r/3k1p2/2p5/pp1pnPp1/P5P1/2P5/2P2BK1/1R6 w - - 0 42
system
You are a chess playing AI.
user
Given the available moves based on the current board state in FEN notation, think carefully about which move would be best, then make that move. Be sure to note your color indicated in the FEN notation before deciding.
## Available Moves
b1a1
b1h1
b1g1
b1f1
b1e1
b1d1
b1c1
b1b5
b1b4
b1b3
b1b2
f2e1
f2a7
f2b6
f2c5
f2d4
f2e3
f2g1
f2h4
f2g3
g2g3
g2g1
g2f1
c3c4
a4b5
f5f6

## Board State Fen
7r/3k1p2/2p5/pp1pnPp1/P5P1/2P5/2P2BK1/1R6 w - - 0 42
assistant
a4b5