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
b2b4
b2b3
d1b3
d1c2
d1h5
d1g4
d1f3
d1e2
d1b1
d1c1
d1e1
f1a6
f1b5
f1c4
f1d3
f1e2
g1h1
a1c1
a1b1
a1a3
a1a2
d2c4
d2e4
d2b1
d2b3
d2f3
f2f4
f2f3
g2g4
g2g3
h2b8
h2c7
h2d6
h2e5
h2f4
h2g3
e3d5
e3f5
e3c2
e3c4
e3g4
h3h4
a4a5

## Board State Fen
2r2bk1/1b1n1ppp/pp2qn2/3p4/P2P4/4N2P/1P1N1PPB/R2Q1BK1 w - - 4 20
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
b2b4
b2b3
d1b3
d1c2
d1h5
d1g4
d1f3
d1e2
d1b1
d1c1
d1e1
f1a6
f1b5
f1c4
f1d3
f1e2
g1h1
a1c1
a1b1
a1a3
a1a2
d2c4
d2e4
d2b1
d2b3
d2f3
f2f4
f2f3
g2g4
g2g3
h2b8
h2c7
h2d6
h2e5
h2f4
h2g3
e3d5
e3f5
e3c2
e3c4
e3g4
h3h4
a4a5

## Board State Fen
2r2bk1/1b1n1ppp/pp2qn2/3p4/P2P4/4N2P/1P1N1PPB/R2Q1BK1 w - - 4 20
assistant
a4a5