The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime.

There are thirteen such primes below 100: 2, 3, 5, 7, 11, 13, 17, 31, 37, 71, 73, 79, and 97.

How many circular primes are there below one million?

#include
    
     #include
     
      #include
      
       #include
       
        #include
        
         #include
         
          bool isprim(int n){ int i=2; for(; i*i
         
        
       
      
     
    

Answer:

55