Consider the following relations A, B, C. How many tuples does the result of the following relational algebra expression contain? Assume that the schema of A U B is the same as that of A. 

Table A
Id Name Age
----------------
12 Arun 60
15 Shreya 24
99 Rohit 11

Table B
Id Name Age
----------------
15 Shreya 24
25 Hari 40
98 Rohit 20
99 Rohit 11

Table C
Id Phone Area
-----------------
10 2200 02 
99 2100 01