2 1 P A R T
Exchange 1, R<->P:  2 1 R A P T
Exchange 2, R<->2:  R 1 2 A P T
Exchange 3, R<->T:  T 1 2 A P R
Exchange 4, R<->A:  T 1 2 R P A
Exchange 5, A<->1:  T A 2 R P 1
Exchange 6, A<->2:  T 2 A R P 1
Exchange 7, A<->P:  T 2 P R A 1
Exchange 8, P<->T:  P 2 T R A 1
Exchange 9, P<->1:  1 2 T R A P