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: Runtime Error)

a, b = gets.chomp.split(' ')
s = gets.chomp

if s.length != a + b + 1
    puts("No")
elsif s[a] != '-'
    puts("No")
else 
  flag = true
  s.each_with_index do |c, i|
    if i != a and (c < '0' || '9' < 0)
      flag = false
      break
    end
    if i == a and c != '-'
      flag = false
      break
    end
  end
  if flag
    puts "Yes"
  else
    puts "No"
  end
end