T1 + S1.
T2 + C1.
T2 != C1.
S2 != O.
S1 != T1.
S1 + O.
S1 != S2.
T2 + C2.
S1 != T2 + C2.
T1 + C1.
S1 != C1.
S1 != T2.
T1 != C1.
T2 != T1.
T1 -> S2.