Solve this interesting problem
TimeLimit: 2000/1000 MS (Java/Others) MemoryLimit: 32768/32768 K (Java/Others)
64-bit integer IO format:%I64d
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Problem Description
Have you learned something about segment tree? If not, don’t worry, I will explain it for you.
Segment Tree is a kind of binary tree, it can be defined as this:
- - For each node u in Segment Tree, u has two values: Lu and Ru.
- If Lu=Ru, u is a leaf node.
- If Lu≠Ru, u has two children x and y,with Lx=Lu,Rx=⌊(Lu+Ru)/2⌋,Ly=⌊(Lu+Ru)/2⌋+1,Ry=Ru.
Here is an example of segment tree to do range query of sum.
Given two integers L and R, Your task is to find the minimum non-negative n satisfy that: A Segment Tree with root node's value Lroot=0 and Rroot=n contains a node u with Lu=L and Ru=R.
Segment Tree is a kind of binary tree, it can be defined as this:
- - For each node u in Segment Tree, u has two values: Lu and Ru.
- If Lu=Ru, u is a leaf node.
- If Lu≠Ru, u has two children x and y,with Lx=Lu,Rx=⌊(Lu+Ru)/2⌋,Ly=⌊(Lu+Ru)/2⌋+1,Ry=Ru.
Here is an example of segment tree to do range query of sum.
Given two integers L and R, Your task is to find the minimum non-negative n satisfy that: A Segment Tree with root node's value Lroot=0 and Rroot=n contains a node u with Lu=L and Ru=R.
Input
The input consists of several test cases.
Each test case contains two integers L and R, as described above.
0≤L≤R≤10^9
L/(R−L+1)≤2015
Each test case contains two integers L and R, as described above.
0≤L≤R≤10^9
L/(R−L+1)≤2015
Output
For each test, output one line contains one integer. If there is no such n, just output -1.
SampleInput
6 7 10 13 10 11
SampleOutput
7 -1 12