#include <bits/stdc++.h>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
template<int mod>istream &operator>>(istream &is,static_modint<mod> &a){long long b;is>>b;a=b;return is;}
istream &operator>>(istream &is,modint &a){long long b;cin>>b;a=b;return is;}
#endif
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) static_cast<void>(0)
#define debugg(...) static_cast<void>(0)
template<typename T1,typename T2>ostream &operator<<(ostream &os,const pair<T1,T2>&p){os<<p.first<<' '<<p.second;return os;}
#endif
using ll=long long;
using ull=unsigned long long;
using P=pair<ll,ll>;
template<typename T>using minque=priority_queue<T,vector<T>,greater<T>>;
template<typename T>bool chmax(T &a,const T &b){return (a<b?(a=b,true):false);}
template<typename T>bool chmin(T &a,const T &b){return (a>b?(a=b,true):false);}
template<typename T1,typename T2>istream &operator>>(istream &is,pair<T1,T2>&p){is>>p.first>>p.second;return is;}
template<typename T>istream &operator>>(istream &is,vector<T> &a){for(auto &i:a)is>>i;return is;}
template<typename T1,typename T2>void operator++(pair<T1,T2>&a,int n){a.first++,a.second++;}
template<typename T1,typename T2>void operator--(pair<T1,T2>&a,int n){a.first--,a.second--;}
template<typename T>void operator++(vector<T>&a,int n){for(auto &i:a)i++;}
template<typename T>void operator--(vector<T>&a,int n){for(auto &i:a)i--;}
#define reps(i,a,n) for(int i=(a);i<(n);i++)
#define rep(i,n) reps(i,0,n)
#define all(x) x.begin(),x.end()
#define pcnt(x) __builtin_popcountll(x)
ll myceil(ll a,ll b){return (a+b-1)/b;}
template<typename T,size_t n,size_t id=0>
auto vec(const int (&d)[n],const T &init=T()){
  if constexpr (id<n)return vector(d[id],vec<T,n,id+1>(d,init));
  else return init;
}
void SOLVE();
int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  #ifdef LOCAL
  clock_t start=clock();
  #endif
  int testcase=1;
  //cin>>testcase;
  for(int i=0;i<testcase;i++){
    SOLVE();
  }
  #ifdef LOCAL
  cerr<<"time:";
  cerr<<(clock()-start)/1000;
  cerr<<"ms\n";
  #endif
}
int op(int x,int y){return 0;}
int e(){return 0;}
int mapping(int f,int x){return max(f,x);}
int composition(int f,int g){return max(f,g);}
int id(){return 0;}
void SOLVE(){
  int h,w;
  cin>>h>>w;
  vector<string>s(h);
  cin>>s;
  vector<vector<int>>dp(h,vector<int>(w,0));
  auto ep(dp),fp(dp),gp(dp);
  rep(i,h)rep(j,w)if(s[i][j]=='#'&&i&&j)dp[i][j]=dp[i-1][j-1]+1;
  rep(i,h)for(int j=w;j--;)if(s[i][j]=='#'&&i&&j!=w-1)ep[i][j]=ep[i-1][j+1]+1;
  for(int i=h;i--;)rep(j,w)if(s[i][j]=='#'&&i!=h-1&&j)fp[i][j]=fp[i+1][j-1]+1;
  for(int i=h;i--;)for(int j=w;j--;)if(s[i][j]=='#'&&i!=h-1&&j!=w-1)gp[i][j]=gp[i+1][j+1]+1;
  using Seg=lazy_segtree<int,op,e,int,mapping,composition,id>;
  vector<Seg>segh(h,Seg(w)),segw(w,Seg(h)),alseg(h+w-1,Seg(min(h,w)));
  rep(i,h)rep(j,w)if(s[i][j]=='#'){
    int mx=max({dp[i][j],ep[i][j],fp[i][j],gp[i][j]});
    if(mx<=1)continue;
    if(i>=j){
      segh[i-j].apply(max(0,j-mx+1),min(w,j+mx),1);
    }
    else{
      segw[j-i].apply(max(0,i-mx+1),min(h,i+mx),1);
    }
    int id=min(i,w-j-1);
    alseg[i+j].apply(max(0,id-mx+1),min(min(h,w),id+mx),1);
  }
  rep(i,h)rep(j,w)if(s[i][j]=='#'){
    if(i>=j){
      if(segh[i-j].get(j))continue;
    }
    else{
      if(segw[j-i].get(i))continue;
    }
    if(alseg[i+j].get(min(i,w-j-1)))continue;
    cout<<"No"<<endl;
    return;
  }
  cout<<"Yes"<<endl;
}