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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;

namespace Algorithm
{
    class Program
    {
        static void Main(string[] args)
        {
            var AB = Console.ReadLine().Split().Select(int.Parse).ToArray();
            var S = Console.ReadLine();
            var isOk = true;
            var number = 0;
            for (var i = 0; i < S.Length; i++)
            {
                if (i == AB[0])
                {
                    if (S[AB[0]] != '-') isOk = false;
                }
                else
                {
                    if (!int.TryParse(S[i].ToString(), out number)) isOk = false;
                }
            }
            Console.WriteLine(isOk ? "Yes":"No");
        }
    }
}