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

Input format
Only line of input consists of a single integer denoting \(n\)

Output format
Print the required answer.

Constraints
\(1 \le Number \; of \; digits \; in \; n \le 10^{5} \)
No leading zeroes are available in \(n\)
\(n \ge 2\)