I want to count how many contracts the company already had in the inventory when the company signs the new contract.

Here is a part of the sample.
id start date end date
1 4/29/2008 7/10/2008
1 11/8/2007 11/2/2008
1 7/11/2008 12/11/2008
1 4/10/2008 10/21/2008
1 1/13/2009 4/9/2009
1 9/6/2007 5/6/2008
1 1/22/2009 6/11/2009
2 7/21/2008 12/31/2008
2 2/13/2008 2/13/2009
2 5/17/2008 10/27/2009
2 3/20/2008 9/11/2008
2 2/13/2013 6/24/2013
In the first row, the company A signed the contract on 4/29/2008 and finished the contract 7/10/2008. So, as of 4/29/2008, the company A already had 3 contracts: 1. 11/8/2007 ~ 11/2/2008, 2. 4/10/2008 ~ 10/21/2018, and 3. 9/6/2007 ~ 5/6/2008.

So, I created two criteria to count how many contract the company already had when the company signs the new contract.
1. other contracts' start dates must be earlier than the contract that the company wants to sign.
2. other contracts' end date must be later than the contract that the company wants to sign. If other contracts' end dates are earlier than the current contract, those contracts were not in the inventory.

I can count the number of contract, using excel function like "=COUNTIFS(B:B,"<"&B2,C:C,">"&B2,A:A,A2)".
id start date end date count
1 4/29/2008 7/10/2008 3
1 11/8/2007 11/2/2008 1
1 7/11/2008 12/11/2008 2
1 4/10/2008 10/21/2008 2
1 1/13/2009 4/9/2009 0
1 9/6/2007 5/6/2008 0
1 1/22/2009 6/11/2009 1
2 7/21/2008 12/31/2008 3
2 2/13/2008 2/13/2009 0
2 5/17/2008 10/27/2009 2
2 3/20/2008 9/11/2008 1
2 2/13/2013 6/24/2013 0

But, I don't know how to count in STATA. Please help me solve this problem.

Thanks!