Solutions :

3-letter words (1 point): 32

AIN; ANA; ANI; ANN; ANT; BUS; CIS; CIT; CUB; INN; INS; NAN; NAS; NAT; NIS; NIT; RIN; RIT; SAI; SAN; SAT; SIC; SIN; SIR; SIT; SRI; SUB; TAN; TAS; TIC; TIN; TIS.

4-letter words (1 point): 35

AINS; ANAN; ANAS; ANIS; ANNA; ANNS; ANSA; ANTA; ANTS; BUST; CIST; CRIS; CRIT; CUBS; INIA; INNS; IRIS; ISNA; NAIN; NANA; NANS; NATS; RINS; SAIN; SANS; SANT; SINS; SIRI; SNIT; TANA; TANS; TICS; TINS; TINT; TRIN.

5-letter words (2 points): 14

ANNAS; ANNAT; ANTAS; BUSTS; CISTS; NANAS; SAINS; SANTS; SNIRT; TANAS; TANNA; TINTS; TRINS; TRIST.

6-letter words (3 points): 7

ANNATS; CITRIN; CRISTA; ISTANA; NITRIC; TANNAS; TANNIC.

7-letter words (7 points): 3

CITRINS; ISTANAS; STANNIC.