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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php
list($a,$b)=explode(" ",trim(fgets(STDIN)));
$s=trim(fgets(STDIN));
if($s[$a]!="-"){
  echo "No";
}else{
  $s[$a]=1;
  $i=0;
  while($i<$a+$b+1){
    if($s[$i]=="-"){
      echo "No";
      exit;
    }
    ++$i;
  }
  echo "Yes";
}