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: Wrong Answer)

using System;
class Program
{
    private bool isnumber(string s,int k)
    {
        char[] num = { '0','1','2','3','4','5','6','7','8','9'};
        int i = Array.IndexOf(num,s[k]);
        return i > 0 ? true : false;
    }
    public static void Main()
    {
        Program prog =new Program();
        string[] str = Console.ReadLine().Split(' ');
        int a, b;
        a = int.Parse(str[0]);
        b = int.Parse(str[1]);
        string s = Console.ReadLine();
        int f = 1;
        if (s[a] != '-')
            f = 0;
        for (int i = 0; i < a; i++)
        {
            if (!prog.isnumber(s, i))
            {
                f = 0;
                break;
            }
        }
        if (f== 1)
        {
            for (int i = a + 1; i < s.Length; i++)
            {
                if (!prog.isnumber(s, i))
                {
                    f = 0;
                    break;
                }
            }
        }
        if (f == 1)
            Console.WriteLine("Yes");
        else
            Console.WriteLine("No");
    }
}