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
a7a5
a7a6
c7b7
c7c1
c7c2
c7c3
c7c4
c7c5
c7c6
c7h7
c7g7
c7f7
c7e7
c7d7
c7c8
f6f7
f6e7
e6e5

## Board State Fen
6R1/p1r5/1p2pk2/1P6/P4PKp/7P/8/8 b - - 8 40
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
a7a5
a7a6
c7b7
c7c1
c7c2
c7c3
c7c4
c7c5
c7c6
c7h7
c7g7
c7f7
c7e7
c7d7
c7c8
f6f7
f6e7
e6e5

## Board State Fen
6R1/p1r5/1p2pk2/1P6/P4PKp/7P/8/8 b - - 8 40
assistant
c7c4