Consider the following function $f(X)$, which takes a single positive integer as argument, and returns an integer.

function f(X): iterations := 0 while X is not 1: if X is even: divide X by 2 else: add 1 to X add 1 to iterations return iterations

It can be shown that for any positive integer $X$, this function terminates. Given an interval $[L, R]$, compute the sum\[ S = f(L) + f(L+1) + \cdots + f(R-1) + f(R)\enspace . \]

-----Input-----
The first and only line of input contains two integers $L$ and $R$ ($1 \leq L \leq R \leq 10^{18}$).

-----Output-----
Output the result $S$ modulo the prime $10^9+7$.

-----Examples-----
Sample Input:
1 127
Sample Output:
1083

Difficulty: competition

Starter code:

Solutions: