Future Iron Man Contest part 1

This problem is a part of a coming set-Future Iron Man Contest

The Difficulty of Problems will keep on increasing exponentially.

Here is the problem-

You have 3 sons and decide to divide 1000 coins among them.In How many ways can you divide these 1000 coins among 3 sons and It is possible for some sons to get zero coins.?Let The Answer to this problem be $M$ .

You have 3 sons and decide to divide 1000 coins among them.In How many ways can You divide these 1000 coins among 3 sons And each son must get at least 3 coins? Let the answer be $N$

Enter Your Answer As $M+N$ .

Note :This question is extremely easy to solve with combinatorics but I suggest Strongly To Use Logic and solve the question And prove your worth to yourself.