Fetch DynamoDb and S3 from lambda function in Java -- 2

Hey, we are working in an AWS account x, s3 bucket that you need to access is in account x,dynamoDb table that you need is present in Account y. Using Java these are the steps that you will need to perform:
1. Fetch dynamoDB from account x(there are many attributes in the table but we need only 1 of them)
2. Fetch s3 bucket from account y.
4. Need to run some queries that require mappings from DB and s3 bucket.
5. Perform some basic calculations.

These are the basic details. Rest all we can discuss later in detail.
Langauge used should be Java only.

pay can be negotiated depending on the quality of the work.