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

namespace AtCoder
{
    class Program
    {
        static void Main(string[] args)
        {
            var x = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
            string s = Console.ReadLine();
            string ans = "Yes";
            for(int i = 0; i < x[0]; i++)
            {
                if (s[i] == '-') ans = "No";
            }
            if (s[x[0]] != '-') ans = "No";
            for(int i = x[0]+1;i<x[1];i++)
            {
                if (s[i] == '-') ans = "No";
            }
            Console.WriteLine(ans);
        }
    }
}