#include <bits/stdc++.h>
using namespace std;

#define int long long
#define rep(i,l,r) for(int i=(int)(l);i<(int)(r);i++)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)x.size())
template<class T>bool chmax(T &a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T &a,T b){if(a>b){a=b;return 1;}return 0;}

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;

const int inf = 1LL<<60;
const int mod = 1e9 + 7;
const double eps = 1e-9;

/*{
  }*/

signed main(){
  int h, w;
  cin >> h >> w;

  vector<string> s(h);
  int black = 0;
  rep(i, 0, h){
    cin >> s[i];
    rep(j, 0, w) if(s[i][j] == '#'){
      black++;
    }
  }

  if(black%2){
    cout << "NO" << endl;
    return false;
  }

  rep(dy, 0, h) rep(dx, 0, w){
    if(!dy and !dx) continue;
    vvi c(h, vi(w));
    if([&](){
      rep(y, 0, h-dy) rep(x, 0, w-dx){
        if(s[y][x] == '#' and !c[y][x]){
          if(s[y+dy][x+dx] == '.' or c[y+dy][x+dx]){
            return true;
          }else{
            c[y][x] = 1;
            c[y+dy][x+dx] = 2;
          }
        }
      }
      return false;
    }()) continue;

    if([&](){
      rep(y, 0, h) rep(x, 0, w){
        if(s[y][x] == '#' and !c[y][x]){
          return true;
        }
      }
      return false;
    }()) continue;

    cout << "YES" << endl;
    return 0;
  }

  cout << "NO" << endl;

  return 0;
}