AI based system that can evaluate handwritten, subjective Math Answer sheets of School students and also give a performance report.

I want a system that can analyse students' handwritten Math answer sheets. The admin should be able to upload the answer key and based on that grading has to be done. The right and wrong parts of the answers should be pointed out, if possible with remarks. The mark then has to be uploaded to our system. This system should have API endpoints that can be used in the pre-existing software that we have.

This system should be able to identify any correct method and award marks for the same.
The length of the answer is a variable and the system should be able to work around that.
Human Effort in the grading part should be very minimum - almost none.