Hi I need to ensure the values unique in range with if possible with a high performance way. Sample data as shown below:

```
A B
1 Serial From - Serial To
2 364500 364600
3 326900 326940
4 120000 120300
5 154700 154800
6 460 480
```

- Table is unsorted
- There are two numbers in each row which always A is less than B
- I always enter new values to next empty row

There musnt be any number that match the any range above. If I enter 120150 and 120700 (because of 4th row) it must give error. How could I do that? I use Excel 2007. Thanks