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"
	"strings"
)

func main() {
	num := "0123456789"
	var a, b int
	var s string
	fmt.Scan(&a, &b, &s)
	if len(s) != a+b+1 {
		fmt.Println("No")
		return
	}
	for i := range s {
		switch {
		case i < a:
			if strings.Index(num, string(s[i])) == -1 {
				fmt.Println("No")
				return
			}
		case i == a:
			if string(s[i]) != "-" {
				fmt.Println("No")
				return
			}
		case a+1 <= i:
			if strings.Index(num, string(s[i])) == -1 {
				fmt.Println("No")
				return
			}
		}
	}
	fmt.Println("Yes")
}