output_description: Print `Yes` if S follows the postal code format in AtCoder Kingdom; print `No`
  otherwise.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      A B
      S
attempt: A,B = [int(x) for x in input().split()]
  S = input()
  flag = True
  for ind,i in enumerate(S):
    if(ind!=A):
        if(ord(i)<48 or 57<ord(i):
           flag = False
           break
    else:
        if(i!='-'):
           flag = False
           break
  if(flag):
           print('Yes')
  else:
           print('No')
problem_description: Statement
  
  The postal code in Atcoder Kingdom is A+B+1 characters long, its (A+1)-th
  character is a hyphen `-`, and the other characters are digits from `0`
  through `9`.
  
  You are given a string S. Determine whether it follows the postal code format
  in Atcoder Kingdom.
samples: [{"input": "3 4\n    269-6650", "output": "Yes\n    \n\nThe (A+1)-th character of S is `-`, and the other characters are digits from\n`0` through `9`, so it follows the format.\n\n* * *"}, {"input": "1 1\n    ---", "output": "No\n    \n\nS contains unnecessary `-`s other than the (A+1)-th character, so it does not\nfollow the format.\n\n* * *"}, {"input": "1 2\n    7444", "output": "No"}]