Given an array of integers, find the one that appears an odd number of times.

There will always be only one integer that appears an odd number of times.

Examples

[7] should return 7, because it occurs 1 time (which is odd).

[0] should return 0, because it occurs 1 time (which is odd).

[1,1,2] should return 2, because it occurs 1 time (which is odd).

[0,1,0,1,0] should return 0, because it occurs 3 times (which is odd).