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 LuaJIT (2.0.4) (judge verdict: Accepted)

function char(s, n)
  return string.sub(s, n, n)
end

n=io.read("*n")
io.read()
s=io.read("*l")

if n%2~=0 then
  print("No")
  os.exit(0)
end

p1={}
for i=1,math.floor(n/2) do
  table.insert(p1, char(s, i))
end

c=1
for i=math.floor(n/2)+1,n do
  if p1[c]~=char(s,i) then
    print("No")
    os.exit(0)
  end
  c=c+1
end

print("Yes")