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)));
$str = trim(fgets(STDIN));
$ok = true;
for($i = 0; $i < $a+$b+1; $i++){
    if($i == $a){
        if($str[$i] != "-")$ok = false;
    }else{
        if(!is_numeric($str[$i]))$ok = false;
    }
}
echo $ok ? "Yes" : "No";