Problem:
Score : 200 points

Problem 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.

Constraints

1≤A,B≤5

|S|=A+B+1

S consists of - and digits from 0 through 9.

Input

Input is given from Standard Input in the following format:

A B
S

Output

Print Yes if S follows the postal code format in AtCoder Kingdom; print No otherwise.

Sample Input 1

3 4
269-6650

Sample Output 1

Yes

The (A+1)-th character of S is -, and the other characters are digits from 0 through 9, so it follows the format.

Sample Input 2

1 1
---

Sample Output 2

No

S contains unnecessary -s other than the (A+1)-th character, so it does not follow the format.

Sample Input 3

1 2
7444

Sample Output 3

No

Solution in Ruby (2.3.3) (judge verdict: Wrong Answer)

a,b = gets.split(" ").map!{|i| i.to_i}
s = gets.split("").map!{|j| j.to_s}
frag = true
s.length.times do |k|
  if k == a
    if s[k] != "-"
      frag = false
    end
  else
    if s[k] =~ /^[0-9]+$/
    else
      frag = false
    end
  end
end
if frag == true
  puts 'Yes'
else 
  puts 'No'
end