Lucy is studying coding algorithm , but she doesn't study well .

According to what she learned, she constructed a coding table for the character set with length .

For example , , she constructed the coding table like this : .

Then , she used the table to compress data .

For example : .

But in some cases, her code will be ambiguous . Such as can decoding as both ``ab'' or ``c'' .

Her physical education teacher found this problem and told her , but she didn't think so .

Now please help her physical education teacher find the minimum length of string , which has at least two decoding methods .

The first line contains one integer  , indicates the size of character set .

Then  lines , the  line contains a  string , represents the code of the  character .

The sum of  will not exceed  , for every pair  , .

If the answer exists , print the answer , otherwise print  instead .

3
0
1
01

2

4
00
01
11
10

-1