Because the number 142 is repeated twice, assume that the number 142142 is called as a repeated number. And, because repeating number 142 is a 3-digit number, 142142 may be called 3rd degree repeated number. 345346 is not a repeated number because no part of the number is repeated. Similarly, 5555 is a repeated number with the degree of 1.

Question:
Write a program that takes a number. And then, it decides the degree of the repeated number.

Input specification:
Firstly, you will be an integer (n) length of the number. Then in the next line, you will have the number where 1 ≤ n ≤ 2000.

Output specification:
Show the minimum degree of repeated number. Show -1, if there is no repetition in the number.