getting count of data from n different tables in teradata

I have n tables .
all tables need not to have
1.same number of columns
2.common columns.

I need to get the count of the data which is union of all the table's data.
for example there are 3 tables a,b,c in which
table 'a' has 3 rows
table 'b' has 4 rows.
table 'c' has 5 rows.

then Result Should be Count of a + Count of b + Count of c
(i.e) 3+4+5 = 12

Ans :
I am doing this by taking 3 tables as example.
we can extend this for any number tables;

select * from a;

*** Query completed. 3 rows found. One column returned.
*** Total elapsed time was 1 second.

col1
-----------
3
1
2

select * from b;

*** Query completed. 4 rows found. 2 columns returned.
*** Total elapsed time was 1 second.

col1 col2
----------- -----------
3 3
1 1
4 4
2 2


select * from c;

*** Query completed. 5 rows found. 3 columns returned.
*** Total elapsed time was 1 second.

col1 col2 col3
----------- ----------- -----------
5 5 5
3 3 3
1 1 1
4 4 4
2 2 2



SELECT SUM(CountTables) FROM
(
SELECT COUNT(*) AS "CountTables" FROM a
UNION
SELECT COUNT(*) AS "CountTables" FROM b
UNION
SELECT COUNT(*) AS "CountTables" FROM c
)t;

*** Query completed. One row found. One column returned.
*** Total elapsed time was 1 second.

Sum(CountTables)
----------------
12