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 = gets.to_i
b = gets.to_i
postal = gets

flag1 = false
flag2 = false
flag3 = false

if postal[a] == "-"
  flag1 = true
end

a+b+1.times do |i|
  if i == a
    next
  elsif postal[i] == "-"
    break
  end
  flag2 = true
end

if postal.length == a+b+2
  flag3 = true
end

if flag1 && flag2 && flag3
  puts "Yes"
else
  puts "No"
end