You are given a large integer value n. Find the largest number x such that \(x \le n\) and all digits of x are prime.

Input:
Only line of input consists of a single integer denoting n.

Output:
Print the required answer.

Constraints:
\(1 \le Number \; of \; digits \; in \; n \le 10^{5} \)
There will be no leading zeroes in n.
\(n \ge 2\)