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"
)

func main() {
    var a, b int
    fmt.Scan(&a, &b)
    var s []byte
    fmt.Scan(&s)
    var ng bool
    for i, c := range s {
        if 0 <= i && i <= a-1 {
            if !isNum(c) {
                ng = true
            }
            continue
        }
        if i == a {
            if c != '-' {
                ng = true
            }
            continue
        }
        if a+1 <= i && i <= a+b {
            if !isNum(c) {
                ng = true
            }
            continue
        }
    }
    if len(s) != a+b+1 {
        ng = true
    }
    if ng {
        fmt.Println("No")
    } else {
        fmt.Println("Yes")
    }
}

func isNum(b byte) bool {
    return '0' <= b && b <= '9'
}