How do I create a cross section between two columns?

[Guest]

I want to make a croos section between two columns on a third column.
Actualy, I have two colums, first one containing a lists of numbers from 1 to
2000 and a second column with 700 numbers from the same range (i.e. 1, 4 ,17,
22, 23 ...). I need a third column that has the difference of 1300 numbers
that do not appear in the second column.
Thanks

 

[Bernard Liengme]

Can you be more specific?

Imagine you have only 10 numbers in A (1...10)
In B you have 7 numbers (are they all at the top; next to corresponding
number in A; randomly arranged?)
In C you want the missing 3 numbers (all at the top; next to holes in B;
next to corresponding numbers in A?)
best wishes