Matias is a student of standard 10 in St. Xavier Int. School. He has to study 7 subjects. In the annual exam, the performance of a student in each subject is graded as “G” (good), “M” (moderate) or “B” (bad). If a student gets at least one B or more than 2 M’s or both, s/he can’t get a scholarship next year. If all three grades are equally likely for Matias, what is the probability that he gets a scholarship next year?