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 OCaml (4.02.3) (judge verdict: Accepted)

let a, b = Scanf.scanf " %d %d" @@ fun a b -> a, b
let s = Scanf.scanf " %s" @@ fun s -> s
let is_digit c = 48 <= Char.code c && Char.code c <= 57
let c = Array.fold_left (+) 0 @@ Array.init (a + b + 1) @@ fun i -> if is_digit s.[i] then 1 else 0
let _ = print_endline @@ if c = a + b && s.[a] = '-' then "Yes" else "No"