Question

Tom & Jerry

3 7

5

Jerry is standing at n=3. As he moves from 3 to 4, energy used is 1. From 4 to 5, energy used is 1. Similarly, as he continues to move towards m=7, the total energy used is 1+1+1+2=5.

Tom has laid out a trap. Jerry is standing at the n^{th} level of mind control. In order to defeat Tom's trap, he needs to reach m^{th} level. The levels are continuous increasing integers. At each increment of level, n^{th} to (n+1)^{th} level, for example, the energy used is - number of distinct prime factors of n.

Jerry needs your help in order to figure out how much total minimum energy he needs to defeat Tom's trap. The total energy is the sum of energy used at each increment of a level.In the calculation of energy, n and m are inclusive.

Input

The only line of input contains the two integers n and m, separated by a single space.

1 ≤ n ≤ m ≤ 10

**Constraints:**1 ≤ n ≤ m ≤ 10

^{6}Output

Return integer denoting the energy needed by Jerry to escape Tom's mind control.

Example

**Sample Input:**

3 7

**Sample Output:**

5

**Explanation**

Jerry is standing at n=3. As he moves from 3 to 4, energy used is 1. From 4 to 5, energy used is 1. Similarly, as he continues to move towards m=7, the total energy used is 1+1+1+2=5.