output_description: Print the length of the shortest string that satisfies the conditions.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      N
      s
      t
attempt: n=int(input())
  s=input()
  t=input()
  if s==t:
      print(n)
  else:
      ans=2*n
      f=True
      for i in range(n):
          for j range(i+1):
              if t[j]==a[n-1-i+j]:
                  f=False
          if not f:
              break
      print(ans)
problem_description: Statement
  
  Snuke is interested in strings that satisfy the following conditions:
  
    * The length of the string is at least N.
    * The first N characters equal to the string s.
    * The last N characters equal to the string t.
  
  Find the length of the shortest string that satisfies the conditions.
samples: [{"input": "3\n    abc\n    cde", "output": "5\n    \n\nThe shortest string is `abcde`.\n\n* * *"}, {"input": "1\n    a\n    z", "output": "2\n    \n\nThe shortest string is `az`.\n\n* * *"}, {"input": "4\n    expr\n    expr", "output": "4\n    \n\nThe shortest string is `expr`."}]