55
{10}
The set of the even elements of [1,15] is: {2, 4, 6, 8, 10, 12, 14}
The set of the odd elements of [1,15] is: {1, 3, 5, 7, 9, 11, 13, 15}
The sum of all the elements of {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} is odd.
The sum of all the elements of {1, 3, 5, 7, 9, 11} is even.