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from time import clock
start=clock()
z=999
a=[0,0,0]
flag=False
for i in range(100000):
	a[0]=int(z/100)
	a[1]=int((z-100*a[0])/10)
	a[2]=int(z-100\*a[0]-10\*a[1])
	palindrome=100000\*a[0]+10000\*a[1]+1000\*a[2]+100\*a[2]+10*a[1]+a[0]

#print(palindrome)
product=999
for j in range(999):
	if palindrome/product<1000 and palindrome%product==0:
		print("the answer is {0}={1}".format(palindrome,product,int(palindrome/product)))
		flag=True
		break
	product=product-1
	z=z-1
	if flag==True or palindrome<0: 
		break
print("{0:5f}s".format(clock()-start))

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def maxPrime():
	n=600851475143
	d=2
	while d<n/d:
		if n%d==0:
			n=int(n/d)
		else:
			d=d+1
	return n

if __name__=="__main__":
	from time import clock
	start=clock()
	finish=clock()
	print("the largest prime factor is {0}\t\t{1}s".format(maxPrime(),(finish-start)/1000000))