Multiplication Problem

In a math lesson, Byteik learned how to multiply and started applying this operation to various numbers. For instance, he would split a number into its digits and calculate the product of these digits. He then became curious about finding the largest product of digits among natural numbers that do not exceed N. Your task is to help solve this problem.

Input

A single integer N (1 ≤ N ≤ 2·10^9).

Output

The maximum product of digits among numbers that do not exceed N.

Examples