Solutions :

3-letter words (1 point): 39

ASP; COS; COT; IOS; ISO; ITS; OCA; PER; PIE; PIU; PSI; PST; PUR; PUS; PUT; REI; REP; REX; RUE; RUT; SAC; SIT; SOC; SOT; SUE; SUI; SUP; SUR; TIS; TIT; TIX; TOC; TUI; TUP; TUX; UPS; URE; UTS; VIE.

4-letter words (1 point): 38

CAST; COIT; COST; COTS; COTT; EXIT; IURE; OAST; OCAS; PIER; PTUI; PUER; PURE; PUTS; PUTT; REPS; RUSA; RUST; RUTS; SCOT; SOCA; SPIE; SPIV; SPUE; SPUR; STOA; SUER; SUIT; SUPE; SURE; TITI; TITS; TOCS; TOIT; TOSA; TUPS; UTIS; VIER.

5-letter words (2 points): 19

ASCOT; ASPER; COAST; COITS; ERUPT; EXITS; PUTTI; REIVE; SITUP; SPIER; SPUER; STOIT; STUPE; STURE; SUPER; TITIS; TITUP; VIPER; XERUS.

6-letter words (3 points): 6

COITUS; ERUPTS; OTITIS; PUTOIS; TITUPS; UPCAST.

7-letter word (7 points): 1

UPCOAST.