An investigator interviewed 100 students to determine their preferences for the three drinks: milk (M), coffee(C) and tea (T). He reported the following : 10 students had all the three drinks M,C,T; 20 had M and C only; 30 had C and T; 12 had M only ; 5 had C only; 8 had T only. Then how many did not take any of three drinks is