Deleting duplicate values in table

I have some duplicate values in my table.i want to delete one of those values

SQL> CREATE TABLE A  (B NUMBER, C VARCHAR(1));

Table created.

SQL> INSERT INTO A VALUES (1, 'A');

1 row created.

SQL> INSERT INTO A VALUES (2, 'B');

1 row created.

SQL> INSERT INTO A VALUES (3, 'C');

1 row created.

SQL> INSERT INTO A VALUES (1, 'A');

1 row created.

SQL> INSERT INTO A VALUES (4, 'D');

1 row created.

SQL> INSERT INTO A VALUES (2, 'B');

1 row created.

SQL> INSERT INTO A VALUES (2, 'B');

1 row created.

SQL> SELECT * FROM A;

B C
---------- -
1 A
2 B
3 C
1 A
4 D
2 B
2 B

Note:
COMBINATION OF (1, A) REPEATS TWICE
COMBINATION OF (2, B) REPEATS THRICE
So, only 3 rows are to be deleted (one of combination 1, A; and two of
combination 2, B)


7 rows selected.

SQL> DELETE FROM A  WHERE (B, C) IN (SELECT B, C -- All records repeating more than once
 FROM (SELECT B, C, SUM(1)  FROM A  GROUP BY B, C
 HAVING SUM(1) > 1))   AND ROWID NOT IN (SELECT MIN(ROWID) RID -- Rows not to be deleted
FROM A  WHERE (B, C) IN (SELECT B, C
FROM (SELECT B, C, SUM(1)  FROM A  GROUP BY B, C  HAVING SUM(1) > 1))
GROUP BY B, C);
3 rows deleted.

SQL> SELECT * FROM A;

B C
---------- -
1 A
2 B
3 C
4 D