Problem:
Score : 300 points

Problem Statement

You are given an integer N.

For two positive integers A and B, we will define F(A,B) as the larger of the following: the number of digits in the decimal notation of A, and the number of digits in the decimal notation of B.

For example, F(3,11) = 2 since 3 has one digit and 11 has two digits.

Find the minimum value of F(A,B) as (A,B) ranges over all pairs of positive integers such that N = A \times B.

Constraints

1 \leq N \leq 10^{10}

N is an integer.

Input

The input is given from Standard Input in the following format:

N

Output

Print the minimum value of F(A,B) as (A,B) ranges over all pairs of positive integers such that N = A \times B.

Sample Input 1

10000

Sample Output 1

3

F(A,B) has a minimum value of 3 at (A,B)=(100,100).

Sample Input 2

1000003

Sample Output 2

7

There are two pairs (A,B) that satisfy the condition: (1,1000003) and (1000003,1). For these pairs, F(1,1000003)=F(1000003,1)=7.

Sample Input 3

9876543210

Sample Output 3

6

Solution in Common Lisp (SBCL 1.1.14) (judge verdict: Wrong Answer)

(defun f (a b)
  (+ 1 (floor (max (log a 10) (log b 10)))))

(defun ans (n)
  (loop :for a :from (floor (sqrt n)) :downto 1
        :do (multiple-value-bind (b mod) (truncate n a)
              (when (zerop mod)
                (return (f a b))))))

(let ((n (parse-integer (read-line))))
  (format t "~d~%" (ans n)))