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)


open Scanf
open Printf

let read_int () = scanf " %d" (fun x -> x)
let rec read_ints n = if n = 0 then [] else let i = read_int () in i :: read_ints (n-1)

let rec for_all_iter a b f = if a >= b then true else f a && for_all_iter (a+1) b f

let () =
  let a = read_int () in let b = read_int () in
  let s = scanf " %s" (fun s -> s) in
  let check1 = for_all_iter 0 a (fun i -> '0' <= s.[i] && s.[i] <= '9') in
  let check2 = s.[a] = '-' in
  let check3 = for_all_iter (a+1) (a+b+1) (fun i -> '0' <= s.[i] && s.[i] <= '9') in
  printf "%s\n" (if check1 && check2 && check3 then "Yes" else "No")