using System;

class Problem_B
{
  public static void Main(string[] args)
  {
    var input = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
    int a = input[0], b = input[1];
    var s = Console.ReadLine();
    if (s.IndexOf("-") != a)
    {
      Console.WriteLine("No");
      return;
    }
    foreach (var c in s)
    {
      if (c == '-') continue;
      if (c < '0' || c > '9')
      {
        Console.WriteLine("No");
        return;
      }
    }
    Console.WriteLine("Yes");
  }
}
