Test your number-theoretic Intuition

Let n be an odd number with n = 1 mod 4. Assume that this number has more than 1ooo Bits. Someone tells you that this number is the product of two large primes.
Test your numbertheoretic intuition by judging whether the following tasks are easy to do using an ordinary desktop computer.
Easy means that you can plug in the number n into a real existing programm, start this program and go for a coffee.
If, after you come back with your coffee, the computer has finished the program and provides a correct answer the problem is considered as easy.

I. Computing four integers a,b,c,d such that n = a2 + b2 + c2+ d2.

Your Choice: easy   difficult   I don't know



II. Computing three integers a,b,c such that n = a2 + b2 + c2.

Your Choice: easy   difficult   I don't know



III. Computing two integers a,b such that n = a2 + b2.

Your Choice: easy   difficult   I don't know