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.chomp.split(" ").map(&:to_i)
s = gets.chomp
flg = 0
sarr = s.chomp.split("")
if sarr[a] == "-" && s.length == a + b + 1
  s.length.times do |i|
    if i != a
      if sarr[i] == "-" then
        flg = 1
     end
   end
  end
end

if flg == 1 then
  print("No\n")
else
  print("Yes\n")
end