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: Accepted)

ab = gets.split(" ").map(&:to_i)
s = gets.chomp
hifnNum = 0

if s.length!=(ab[0]+ab[1]+1)
  puts "No"
  exit
end

(s.length).times do |i|
  if s[i] =="-"
    hifnNum = hifnNum+1
  end
end

if hifnNum !=1
  puts "No"
  exit
end


if s[(ab[0]+1)-1] != "-"
  puts "No"
  exit
end

puts "Yes" if (s.length - ab[0] -1) == ab[1] ;