title
Parity Decider

description
Accepts the input if there are an even number of a's.

vertices
0 R 0.25 0.3
1 R 0.75 0.3
2 Y 0.25 0.75
3 N 0.75 0.75

edges
0 1 a a 0.3
0 2 # #
1 0 a a 0.3 
1 3 # #

tapes
[a] b a a b a a a 
[a] a a a a b b b 
[b] a b b b a 
[b] a b 
[a] a a a b