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 (2.7.1) (judge verdict: Accepted)

a,b = gets.chomp.split(' ').map(&:to_i)
s = gets.chomp.chars
i = 0
while i < a
  unless /["0""1""2""3""4""5""6""7""8""9"]/ =~ s[i]
    ans = "No"
    break
  end
  i += 1
end
if s[i] != "-"
  ans = "No"
end
i += 1
while i < a + b + 1
  unless /["0""1""2""3""4""5""6""7""8""9"9"]/ =~ s[i]
    ans = "No"
    break
  end
  i += 1
end
if ans == "No"
  puts ans
else
  puts "Yes"
end