Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE Assets ( maintenance_contract_id VARCHAR )
TABLE: CREATE TABLE Maintenance_Contracts ( maintenance_contract_id VARCHAR )

### Question ###
How many assets does each maintenance contract contain? List the number and the contract id.

### Accurate SQL ###

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