A tape drive writes a running parity checksum by XOR-ing together every block index in a contiguous span. Given the span endpoints L and R, compute the bitwise XOR of all integers from L to R inclusive.
Input format
Line 1: two space-separated integers L and R.
Output format
A single integer: L xor (L+1) xor ... xor R.
Constraints
- 0 <= L <= R <= 1000000000