#include <bits/stdc++.h>
using namespace std;
#define REP(i,N) for(i=0;i<N;i++)
typedef long long ll;
typedef pair<int, int> P;
typedef struct{
  int first;
  int second;
  int third;
}T;

//昇順
bool comp_Se(T& l, T& r){
  return l.second < r.second;
}

int H,W;
vector<char>S;
vector<int> v;

//cur 新しく赤を塗った位置
//dx,dy移動先
bool dfs(int cur, int dx, int dy, vector<char>color){
  int j = v[cur]%H+dx, k = v[cur]/H+dy;
  //移動先が範囲外j
  if(j >= H || k >=W || k < 0) return false;
  //移動先が黒じゃない
  int l = k*H+j;
  if(color[l] != '#') return false;
  //青で塗る
  color[l] = 'B';
  //次の黒を探す(
  cur++;
  while( cur != v.size() && color[v[cur]] != '#') cur++;

  if(cur==v.size()) return true;
  color[v[cur]] = 'R';
  return dfs(cur, dx, dy, color);
}

int main(void){
  cin >> W >> H;
  S = vector<char>(W*H);
  int i;
  REP(i,H*W){
    cin >> S[i];
    if(S[i] == '#') v.push_back(i);
  }

  //黒がないまたは奇数なら作れない
  if(v.size()%2 || v.size() == 0){
    cout << "NO" << endl;
    return 0;
  }

  //以降黒は2以上の偶数

  vector<char> color = S;
  color[v[0]] = 'R';
  for(i=1;i<v.size();i++){
    int dx = v[i]%H - v[0]%H, dy = v[i]/H - v[0]/H;
    if(dfs(0,dx,dy,color)){   
      cout << "YES" << endl;
      return 0;
    }
  }
  cout << "NO" << endl;
  return 0;
}