class PrimeNumbersIterator(Iterator):
    def __init__(self,start,end):
        self.start = start-1
        self.end = end

    def IsPrimeNumbers(self,k):
        if k <= 2:
            return False
        x = int(math.sqrt(k))+1
        for i in xrange(2,x):
            if k%i == 0:
                return False
        return True       
        
    def next(self):
        if self.start >= self.end:
            raise StopIteration
        else:
            self.start+=1 
            if self.IsPrimeNumbers(self.start) == True:
                return self.start

class PrimeNumbersIterable(Iterable):
    def __init__(self,start,end):
        self.start = start 
        self.end = end
    
    def __iter__(self):
        return PrimeNumbersIterator(self.start,self.end)

t = PrimeNumbersIterable(1,20)
for i in t:
    print i,