100 PRINT "Police","San.","Fire"
110 FOR P=2 TO 7 STEP 2
120   FOR S=1 TO 7
130     IF S<>P THEN
131       LET F=(12-P)-S
140       IF F>0 AND F<=7 AND F<>S AND F<>P THEN PRINT P,S,F
141     END IF
150   NEXT
160 NEXT