printРабочее место участника


1929. Strength

Ограничения: время – 1s/2s, память – 64MiB Ввод: input.txt или стандартный ввод Вывод: output.txt или стандартный вывод copy
Послать решение Blockly Посылки Темы Где Обсудить (0)

Let us begin with a positive integer `N` and find the smallest positive integer which doesn't divide `N`. If we repeat the procedure with the resulting number, then again with the new result and so on, we will eventually obtain the number 2 (two). Let us define `"strength"(N)` as the length of the resulting sequence.
For example, for `N\ =\ 6` we obtain the sequence `6,\ 4,\ 3,\ 2` which consists of 4 numbers, thus `"strength"(6)\ =\ 4`.
Given two positive integers `A\ \ <\ \ B`, calculate the sum of strengths of all integers between `A` and `B` (inclusive), that is,
`"strength"(A)\ +\ "strength"(A\ +\ 1)\ +\ …\ +\ "strength"(B)`.
The first and only line of input contains two positive integers, `A` and `B` (`3\ ≤\ A\ <\ B\ <\ 10^17`).
The first and only line of output should contain the requested sum of strengths.

Sample Input #1

3 6

Sample Output #1


Sample Input #2

100 200

Sample Output #2

Source: COCI 2012/2013, contest #1