Problems

# "Mirror prime" numbers

# "Mirror prime" numbers

We will call a number "mirror prime", if it is prime, and the number written in a reverse order is also prime.

Find the number of "mirror primes" from **a** to **b**.

#### Input

Two integers **a** and **b** (**1** ≤ **a** ≤ **b** ≤ **10000**).

#### Output

Print the number of "mirror primes" from **a** to **b** inclusive.

Input example #1

10 25

Output example #1

3