Problem:
Score : 200 points

Problem Statement

Given are a positive integer N and a string S of length N consisting of lowercase English letters.

Determine whether the string is a concatenation of two copies of some string.
That is, determine whether there is a string T such that S = T + T.

Constraints

1 \leq N \leq 100

S consists of lowercase English letters.

|S| = N

Input

Input is given from Standard Input in the following format:

N
S

Output

If S is a concatenation of two copies of some string, print Yes; otherwise, print No.

Sample Input 1

6
abcabc

Sample Output 1

Yes

Let T = abc, and S = T + T.

Sample Input 2

6
abcadc

Sample Output 2

No

Sample Input 3

1
z

Sample Output 3

No

Solution in Ruby (2.3.3) (judge verdict: Accepted)

def main(argv)
  n = gets.chomp.to_i
  s = gets.chomp
  
  flag = false
  if (n % 2) == 0 then
    m = n / 2
    t = s[0...m]
    flag = (s == (t + t))
  end
  
  puts (flag ? 'Yes' : 'No')
end

if self.to_s == 'main' then
  main(ARGV)
end