B. Nirvanatime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputKurt reaches nirvana when he finds the product of all the digits of some positive integer. Greater value of the product makes the nirvana deeper.Help Kurt find the maximum possible product of digits among all integers from 1 to n.InputThe only input line contains the integer n (1 \le n \le 2\cdot10^9).OutputPrint the maximum product of digits among all integers from 1 to n.ExamplesInput
390
Output
216
Input
7
Output
7
Input
1000000000
Output
387420489
NoteIn the first example the maximum product is achieved for 389 (the product of digits is 3\cdot8\cdot9=216).In the second example the maximum product is achieved for 7 (the product of digits is 7).In the third example the maximum product is achieved for 999999999 (the product of digits is 9^9=387420489).
390

216 
['brute force', 'math', 'number theory', '*1200']