I need help with this maths question and no one can help me!!!

The set {1,2,3,4} can be partitioned into two subsets {1,4} and {2,3} of the same size. Notice that 1+4 = 2+3

a)Find the next whole numbern, above 4, for which the set {1,2,...,n} can be partitioned into two subsets S and T of the same size, with the sum of the numbers in S equal to the sum of the numbers in T

b)Find all partitions inawith theadditionalproperty of that the sum of the squares of the numbers in S equals the sum of the squares of the numbers T

thanks in advance

Chuck