题目描述

“Drat!” cursed Charles. “This stupid carry bar is not working in my Engine! I just tried to calculate the square of a number, but it’s wrong; all of the carries are lost.”

“Hmm,” mused Ada, “arithmetic without carries! I wonder if I can figure out what your original input was, based on the result I see on the Engine.”

Carryless addition, denoted by ⊕, is the same as normal addition, except any carries are ignored (in base 10). Thus, 37⊕48 is 75, not 85.

Carryless multiplication, denoted by ⊗, is performed using the schoolboy algorithm for multiplication, column by column, but the intermediate additions are calculated using carryless addition. More formally, Let be the digits of a, where is its least significant digit. Similarly define be the digits of b. The digits of c=a⊗b are given by the following equation:

mod 10,

where any or is considered zero if i>m or j>n. For example, 9⊗1234 is 98769876, 90⊗1234 is 9876098760, and 99⊗1234 is 9753697536.

输入格式

The input consists of a single line with a positive integer N, with at most 25 digits and no leading zeros

输出格式

Print, on a single line, the least positive number aa such that a⊗a=N. If there is no such a, print ‘-1’ instead.

样例

输入样例1

6

输出样例1

4

输入样例2

149

输出样例2

17

输入样例3

123476544

输出样例3

11112

输入样例4

15

输出样例4

-1