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

vector<string> solve(vector<string> &S) {
    int H = S.size();
    int W = S.back().size();
    vector ru(H, vector<int>(W, -1));
    vector ld(H, vector<int>(W, -1));
    for( int i = 0; i < H; i++ ) {
        for( int j = 0; j < W; j++ ) {
            if( S[i][j] == '.' ) continue;
            ru[i][j] = 0;
            if( i-1 >= 0 && j+1 < W ) ru[i][j] = max(0, ru[i-1][j+1]+1);
        }
    }
    for( int i = H-1; i >= 0; i-- ) {
        for( int j = W-1; j >= 0; j-- ) {
            if( S[i][j] == '.' ) continue;
            ld[i][j] = 0;
            if( i+1 < H && j-1 >= 0 ) ld[i][j] = max(0, ld[i+1][j-1]+1);
        }
    }
    unordered_map<int, vector<pair<int, int>>> mp;
    for( int i = 0; i < H; i++ ) {
        for( int j = 0; j < W; j++ ) {
            mp[i-j].push_back(make_pair(i, j));
        }
    }
    vector<string> ret(H, string(W, '.'));
    for( auto [_key, v] : mp ) {
        int K = v.size();
        vector<int> imos(K+1);
        for( int k = 0; k < K; k++ ) {
            auto [i, j] = v[k];
            int t = min(ru[i][j], ld[i][j]);
            if( t < 1 ) continue;
            imos[max(0, k-t)]++;
            imos[min(K, k+t+1)]--;
        }
        for( int k = 0; k < K; k++ ) {
            auto [i, j] = v[k];
            imos[k+1] += imos[k];
            if( imos[k] > 0 ) ret[i][j] = '#';
        }
    }
    return ret;
}

int main() {
    int H, W;
    cin >> H >> W;
    vector<string> S(H), R(H);
    for( int i = 0; i < H; i++ ) {
        cin >> S[i];
        R[i] = S[i];
        reverse(R[i].begin(), R[i].end());
    }
    vector<string> A = solve(S);
    vector<string> B = solve(R);
    for( int i = 0; i < H; i++ ) {
        reverse(B[i].begin(), B[i].end());
    }
    // for( auto _dbg : A ) cout << _dbg << endl;
    // cout << "----" << endl;
    // for( auto _dbg : B ) cout << _dbg << endl;
    // cout << "----" << endl;
    for( int i = 0; i < H; i++ ) {
        for( int j = 0; j < W; j++ ) {
            if( S[i][j] =='#' && A[i][j] == '.' && B[i][j] == '.' ) {
                cout << "No" << endl;
                return 0;
            }
        }
    }
    cout << "Yes" << endl;
}