Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE Assets (maintenance_contract_id VARCHAR); CREATE TABLE Maintenance_Contracts (maintenance_contract_id VARCHAR)
### Question:
How many assets does each maintenance contract contain? List the number and the contract id.
### Answer:
SELECT COUNT(*), T1.maintenance_contract_id FROM Maintenance_Contracts AS T1 JOIN Assets AS T2 ON T1.maintenance_contract_id = T2.maintenance_contract_id GROUP BY T1.maintenance_contract_id