#include<bits/stdc++.h>
using namespace std;
int main(){
  int a,b;
  cin>>a>>b;
    string h;
    cin>>h;
  for(int m=1;m<a*b-a-2;m++){
    if(h[m]=='#'){
      if(h[m+1]=='#'||h[m-1]=='#'||h[m+a]=='#'||h[m-a]=='#'){
  for(int i=1;i<a*b-a-2;i++){
    if(h[i]=='#'&&h[i-1]!='#'&&h[i+1]!='#'&&h[i+a]!='#'&&h[i-a]!='#'){
      cout<<"No"<<endl;
      return 0;
    }
    else{
    cout<<"Yes"<<endl;
      return  0;
    }
  }
      }
  }
    }
      cout<<"Yes"<<endl;
}
}
