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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"fmt"
	"unicode"
)

func are_digits(s string) bool {
	for _, r := range s {
		if !unicode.IsDigit(r) {
			return false
		}
	}
	return true
}

func main() {
	var a, b int
	var s string
	fmt.Scan(&a, &b)
	fmt.Scan(&s)

	if are_digits(s[:a]) && are_digits(s[a+1:]) && s[a] == '-' {
		fmt.Println("Yes")
	} else {
		fmt.Println("No")
	}
}