You are given two positive integers $l$ and $r$,you shoud answer $l⊕(l+1)⊕⋯ ⊕r$,where $⊕$ denotes the bitwise $XOR$ operation. In $XOR$ operation we perform the comparison of two bits, being $1$ if the two bits are different, and $0$ if they are the same. For example:

$0101⊕0011=0110$

Note that binary code $0101,0011$ and $0110$ are $5,3$ and $6$ in decimal.

The input contain two integers $l ,r (1 ≤ l ≤ r ≤10^{18})$.

The only output line should contain a single integer.

$3⊕4⊕5⊕6=4$