def prime():
    i = 2 #the first index
    numToTest = 5 #the first candidate prime
    listOfPrimes = [] #list of primes
    for i in range (2, 1001):
        if (numToTest-1)%6 == 0:
            listOfPrimes.append(numToTest) #it's prime. put in list
            numToTest += 2 #go to next odd number
            i += 1 #go to next index
        elif (numToTest+1)%6 == 0:
            listOfPrimes.append(numToTest) #it's prime. put in list
            i += 1 #go to next index
            numToTest += 2 #go to next odd number
        else:
            numToTest += 2 #go to next odd number
    print listOfPrimes[-1]