Balanced number is a number whose sum of the digits in the first half is the same as sum of the digits in the second half. For example: 735465 is balanced number with the length three. However, the number 732523 is not a balanced number because sum of the digits in the first half (732) is 12 and sum of the digits in the second half (523) is 10.

The number may be balanced with only the divisors of the length given. For example, for the length 9, the number may be balanced with the lengths 1, 2 and 3. For example, the number 732855 is another balanced number with the length 2 (sum of the digits (7+3)==(2+8)==(5+5)==10). 5555 is also balanced number with the length 1.

Question:
Write a program that gets an n-digit number and then it decides the minimum length of the balance for the given number.

Input specification
Firstly, you will be given an integer: n the length of given number where 1 ≤ n ≤ 250. Then, in the next line, you will be given the number.

Output specification
Show the minimum length of balance. Show -1, if it is not balanced in any length.