#include<bits/stdc++.h>
using namespace std;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
template<class T> using V = vector<T>;
template<class T> using VV = V<V<T>>;
template<class T> using VVV = V<VV<T>>;
template<class T> using VVVV = VV<VV<T>>;
#define rep(i,n) for(ll i=0ll;i<n;i++)
#define REP(i,a,n) for(ll i=a;i<n;i++)
const long long INF = (1LL << 60);
const long long mod99 = 998244353;
const long long mod107 = 1000000007;
const long long mod = mod99;
#define eb emplace_back
#define pb eb
#define be(v) (v).begin(),(v).end()
#define all(i,v) for(auto& i : v)
#define all2(i,j,v) for(auto& [i,j] : v)
template<class T, class U> void chmin(T& t, const U& u) { if (t > u) t = u; }
template<class T, class U> void chmax(T& t, const U& u) { if (t < u) t = u; }

// cin.tie(nullptr);
// ios::sync_with_stdio(false);
// cout << fixed << setprecision(20);

void solve(){
  ll h,w;
  cin >> h >> w;
  V<string> v(h);
  rep(i,h) cin >> v[i];
  string ans = "NO";
  rep(i,h) rep(j,w) if(i+j){
  	ll f = 1;
  	VV<ll> p(h, V<ll>(w, 0));
  	rep(x, h) rep(y, w)	if(v[x][y] == '#' && !p[x][y]){
  		p[x][y] = 1;
  		if((x+i>=h || y+j>=w) || v[x+i][y+j] == '.') f = 0;
  		else p[x+i][y+j] = 2;
  	}
  	if(f) ans = "YES";
  }
  rep(i,h) rep(j,w) if(i+j){
  	ll f = 1;
  	VV<ll> p(h, V<ll>(w, 0));
  	rep(x, h) rep(y, w)	if(v[x][y] == '#' && !p[x][y]){
  		p[x][y] = 1;
  		if((x-i<0 || y+j>=w) || v[x-i][y+j] == '.') f = 0;
  		else p[x-i][y+j] = 2;
  	}
  	if(f) ans = "YES";
  }
  ll cnt = 0;
  rep(i, h) all(c,v[i]) if(c=='#') cnt++;
  if(!cnt) ans = "NO";
  cout << ans << endl;
}





int main(){
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  int t=1;
  // cin >> t;
  rep(i,t) solve();
}