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 Haskell (GHC 7.10.3) (judge verdict: Accepted)

module Main where

import Control.Applicative
import Control.Monad
import Data.List
import Data.Char

main :: IO ()
main = do
    [a, b] <- fmap read . words <$> getLine :: IO [Int]
    ss <- getLine
    let c1 = take a ss
    let c2 = head $ drop a ss
    let c3 = take b $ drop (a + 1) ss
    if and [ all isAlphaNum c1
           , c2 == '-'
           , all isAlphaNum c3
           ]
        then putStrLn "Yes"
        else putStrLn "No"