#include <bits/stdc++.h>

using namespace std;

#define overload4(_1, _2, _3, _4, name, ...) name
#define rep1(n) for(int i = 0; i < (int)(n); ++i)
#define rep2(i, n) for(int i = 0; i < (int)(n); ++i)
#define rep3(i, a, b) for(int i = (a); i < (int)(b); ++i)
#define rep4(i, a, b, c) for(int i = (a); i < (int)(b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)

#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; --i)
#define ALL(a) (a).begin(), (a).end()
#define Sort(a) (sort((a).begin(), (a).end()))
#define RSort(a) (sort((a).rbegin(), (a).rend()))
#define UNIQUE(a) (a.erase(unique((a).begin(), (a).end()), (a).end()))

typedef long long int ll;
typedef unsigned long long ul;
typedef long double ld;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef vector<char> vc;
typedef vector<string> vst;
typedef vector<double> vd;
typedef vector<long double> vld;
typedef pair<long long, long long> P;

template<class T> long long sum(const T& a){ return accumulate(a.begin(), a.end(), 0LL); }
template<class T> auto min(const T& a){ return *min_element(a.begin(), a.end()); }
template<class T> auto max(const T& a){ return *max_element(a.begin(), a.end()); }

const long long MINF = 0x7fffffffffff;
const long long INF = 0x1fffffffffffffff;
const long long MOD = 998244353;
const long double EPS = 1e-9;
const long double PI = acos(-1);
 
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

template<typename T1, typename T2> istream &operator>>(istream &is, pair<T1, T2> &p){ is >> p.first >> p.second; return is; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){ os << "(" << p.first << ", " << p.second << ")"; return os; }
template<typename T> istream &operator>>(istream &is, vector<T> &v){ for(T &in : v) is >> in; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v){ for(int i = 0; i < (int) v.size(); ++i){ os << v[i] << (i + 1 != (int) v.size() ? " " : ""); } return os; }
template <typename T, typename S> ostream &operator<<(ostream &os, const map<T, S> &mp){ for(auto &[key, val] : mp){ os << key << ":" << val << " "; } return os; }
template <typename T> ostream &operator<<(ostream &os, const set<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &st){ auto itr = st.begin(); for(int i = 0; i < (int)st.size(); ++i){ os << *itr << (i + 1 != (int)st.size() ? " " : ""); itr++; } return os; }
template <typename T> ostream &operator<<(ostream &os, queue<T> q){ while(q.size()){ os << q.front() << " "; q.pop(); } return os; }
template <typename T> ostream &operator<<(ostream &os, deque<T> q){ while(q.size()){ os << q.front() << " "; q.pop_front(); } return os; }
template <typename T> ostream &operator<<(ostream &os, stack<T> st){ while(st.size()){ os << st.top() << " "; st.pop(); } return os; }
template <class T, class Container, class Compare> ostream &operator<<(ostream &os, priority_queue<T, Container, Compare> pq){ while(pq.size()){ os << pq.top() << " "; pq.pop(); } return os; }

template<class T, class U> inline T vin(T& vec, U n) { vec.resize(n); for(int i = 0; i < (int) n; ++i) cin >> vec[i]; return vec; }
template<class T> inline void vout(T vec, string s = "\n"){ for(auto x : vec) cout << x << s; }
template<class... T> void in(T&... a){ (cin >> ... >> a); }
void out(){ cout << '\n'; }
template<class T, class... Ts> void out(const T& a, const Ts&... b){ cout << a; (cout << ... << (cout << ' ', b)); cout << '\n'; }
template<class T, class U> void inGraph(vector<vector<T>>& G, U n, U m, bool directed = false){ G.resize(n); for(int i = 0; i < m; ++i){ int a, b; cin >> a >> b; a--, b--; G[a].push_back(b); if(!directed) G[b].push_back(a); } }

template <typename T>
struct CumulativeSum2D{
    vector<vector<T>> data;

    CumulativeSum2D(const int H, const int W) : data(H + 3, vector<T>(W + 3, 0)) {}

    void add(int i, int j, const T &z){
        ++i, ++j;
        if(i >= (int) data.size() || j >= (int) data[0].size()) return;
        data[i][j] += z;
    }

    void imos(const int i1, const int j1, const int i2, const int j2, const T &z = 1) {
        add(i1, j1, z);
        add(i1, j2, -z);
        add(i2, j1, -z);
        add(i2, j2, z);
    }

    void build(){
        for(int i = 1; i < (int) data.size(); ++i){
            for(int j = 1; j < (int) data[i].size(); ++j){
                data[i][j] += data[i][j - 1] + data[i - 1][j] - data[i - 1][j - 1];
            }
        }
    }

    inline T imos_get(const int i, const int j) const{
        return data[i + 1][j + 1];
    }

    inline T sum(const int i1, const int j1, const int i2, const int j2) const {
        return (data[i2][j2] - data[i1][j2] - data[i2][j1] + data[i1][j1]);
    }
};

ll h, w;
vst s;

void input(){
    in(h, w);
    vin(s, h);
}

void solve(){
    vector<vll> cs1(h, vll(w)), cs2(h, vll(w));
    vector<vll> imos1(h, vll(w)), imos2(h, vll(w));
    rep(i, h){
        rep(j, w){
            if(s[i][j] == '#'){
                cs1[i][j] = 1;
                cs2[i][j] = 1;
            }
        }
    }
    rep(i, h) rep(j, w){
        if(i + 1 < h && j + 1 < w){
            cs1[i + 1][j + 1] += cs1[i][j];
        }
        if(i + 1 < h && 0 <= j - 1){
            cs2[i + 1][j - 1] += cs2[i][j];
        }
    }
    auto check = [&](ll x, ll y){
        if(0 <= x && x < h && 0 <= y && y < w){
            return true;
        }
        return false;
    };
    rep(i, h) rep(j, w){
        if(s[i][j] == '.') continue;
        ll ok = 0, ng = 1000000;
        while(abs(ok - ng) > 1){
            ll mid = (ok + ng) / 2;

            ll v1 = 0, v2 = 0;
            {
                ll x1 = i + mid, y1 = j + mid;
                ll x2 = i - mid - 1, y2 = j - mid - 1;
                if(check(x1, y1)) v1 += cs1[x1][y1];
                if(check(x2, y2)) v1 -= cs1[x2][y2];
            }
            {
                ll x1 = i + mid, y1 = j - mid;
                ll x2 = i - mid - 1, y2 = j + mid + 1;
                if(check(x1, y1)) v2 += cs2[x1][y1];
                if(check(x2, y2)) v2 -= cs2[x2][y2];
            }
            if(v1 != 2 * mid + 1 || v2 != 2 * mid + 1){
                ng = mid;
            }else{
                ok = mid;
            }
        }
        if(ok == 0) continue;
        imos1[i - ok][j - ok]++;
        if(check(i + ok + 1, j + ok + 1)) imos1[i + ok + 1][j + ok + 1]--;
        imos2[i - ok][j + ok]++;
        if(check(i + ok + 1, j - ok - 1)) imos2[i + ok + 1][j - ok - 1]--;
    }
    rep(i, h) rep(j, w){
        if(i + 1 < h && j + 1 < w){
            imos1[i + 1][j + 1] += imos1[i][j];
        }
        if(i + 1 < h && 0 <= j - 1){
            imos2[i + 1][j - 1] += imos2[i][j];
        }
    }

    string ans = "Yes";
    rep(i, h) rep(j, w){
        if(s[i][j] == '#'){
            if(imos1[i][j] == 0 && imos2[i][j] == 0){
                ans = "No";
            }
        }
    }
    out(ans);
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(20);
    
    input();
    solve();
}