12 人解决，21 人已尝试。
14 份提交通过，共有 74 份提交。
6.4 EMB 奖励。
单点时限: 1.0 sec
内存限制: 512 MB
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
$$S = f(L) + f(L+1) + \cdots + f(R-1) + f(R)$$
The first and only line of input contains two integers $L$ and $R$ ($1 \leq L \leq R \leq 10^{18}$).
Output the result $S$ modulo the prime $10^9+7$.
1 127
1083
74 74
11
12 人解决，21 人已尝试。
14 份提交通过，共有 74 份提交。
6.4 EMB 奖励。