import threading;
import queue;
import sys;

#------------------------------------------------------------------------------#

class PrimeWorker(threading.Thread): 

    def __init__(self,number,getNextNumber): 
        threading.Thread.__init__(self); 
        self.MyPrime=number;
        self.MyGetter=getNextNumber;
        self.MyQueue=queue.Queue();
 
    def run(self):
        while True:
            nb=self.MyGetter();
            if nb==0:
                return;
            if nb % self.MyPrime != 0:
                break;
        # end while

        with primeNumbersLock:
            primeNumbers.append(nb);

        getNextNumber=self.MyQueue.get;
        nextWorker=PrimeWorker(nb,getNextNumber);
        with allThreadsLock:
            allThreads.append(nextWorker);
        nextWorker.start();

        while True:
            nb=self.MyGetter();
            if nb==0:
                self.MyQueue.put(0);
                break;
            if nb % self.MyPrime != 0:
                self.MyQueue.put(nb);
        # end while
         
    # end def
# end class

#------------------------------------------------------------------------------#
 
class FirstWorker(threading.Thread): 

    def __init__(self,maxNumber): 
        threading.Thread.__init__(self); 
        self.MaxNumber=maxNumber;
        self.MyQueue=queue.Queue();
 
    def run(self):
        nb=3;
        getNextNumber=self.MyQueue.get;
        thread=PrimeWorker(nb,getNextNumber);
        with allThreadsLock:
            allThreads.append(thread);
        thread.start();

        nb+=2;
        while nb<=self.MaxNumber:
            self.MyQueue.put(nb);
            nb+=2;
        # end while
        
        self.MyQueue.put(0);
    # end def
# end class

#------------------------------------------------------------------------------#

def getPrimeTwins(pList):
    twinsList=[];
    lastNb=3;
    for nb in pList:
        if nb==lastNb+2:
            twinsList.append((lastNb,nb));
        lastNb=nb;
    # end for
    return twinsList;
# end def

#------------------------------------------------------------------------------#

def getNumberInput():
    infoStr="# Enter the largest 'number' for sieving ..."
    errorStr="# Enter a 'number' > 2 OR 'e' for exit ...";
    print(infoStr);
    while True:
        inputData=input("N> ");
        inputData.strip();

        if inputData.isdigit():
            nb=int(inputData);
            if nb>2:
                userData=('number',nb);
                break;
        elif inputData.isalpha():
            if inputData=='e':
                userData=('command',inputData);
                break;
            # end if
        # end if
        print(errorStr);
    # end while
                
    return userData;
# end def

#------------------------------------------------------------------------------#
#------------------------------------------------------------------------------#

if __name__ == '__main__':
    print('\n# Beginning...');

#------------------------------------------------------------------------------#

    infoStr="# Largest number is: "

    while True:
        (taskKind,taskData)=getNumberInput();
        
        if taskKind=='number':
            print(infoStr,taskData,'\n');

            allThreads=[];
            allThreadsLock=threading.Lock();
            primeNumbers=[2,3];
            primeNumbersLock=threading.Lock();

            thread=FirstWorker(taskData);
            with allThreadsLock:
                allThreads.append(thread);
            thread.start(); 
            for myThread in allThreads: 
                myThread.join();
                
        elif taskKind=='command':
            if taskData=='e':
                print('# Exit by user');
                sys.exit();
            else:
                pass;
            # end if
        # end if
        
        nbPrimes=len(primeNumbers);
        print('> Number of primes: ',nbPrimes);

        twinsList=getPrimeTwins(primeNumbers);
        nbTwins=len(twinsList);
        print('> Number of twins: ',nbTwins);
        print('\n> The prime twins are: ');
        print(twinsList,'\n');
    # end while

#------------------------------------------------------------------------------#
    print('# Finished.\n');
# end if main