emirpMinion

Emirp is prime spelled backwards.

A number is emirp if both the number itself and the same number written backwards are prime. For instance, 13and 31 are emirps, but 23 is not, since 32 is a composite number.

Emirps are hiding in a large integer num, waiting for the next skilled programmer to find them! They are clustered together, so an emirp can be formed from a set of consecutive digits of num.

Find the sum of all emirps in num. If none can be found, return -1 instead.

Example

• For num = 13211, the output should be emirpMinion(num) = 1350.
  In this example, 13, 3, 2, 1321, and 11 are the only emirps, and their sum is 13 + 3 + 2 + 11 + 1321 = 1350.

Input/Output

• [execution time limit] 0.5 seconds

• [input] integer num

  Large integer where emirps are hiding.

  Constraints:
  
  10 ≤ num ≤ 2 · 109.

• [output] integer

  • Sum of all emirps found in the large integer num.