#include<bits/stdc++.h>
using namespace std;
int main(){
  int a,b;
  cin>>a>>b;
    string h;
    cin>>h;
  for(int i=0;i<a*b;i++)
    if(h[i]=='#'&&h[i-1]!='#'&&h[i+1]!='#'&&h[i+a]!='#'&&h[i-a]!='#'){
      cout<<"Yes"<<endl;
      return 0;
    }
  }
cout<<"No"<<endl;
}