#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));
    vector lu(H, vector<int>(W, -1));
    vector rd(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] = lu[i][j] = 0;
            if( i-1 >= 0 && j+1 < W ) ru[i][j] = ru[i-1][j+1]+1;
            if( i-1 >= 0 && j-1 >= 0 ) lu[i][j] = lu[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] = rd[i][j] = 0;
            if( i+1 < H && j-1 >= 0 ) ld[i][j] = ld[i+1][j-1]+1;
            if( i+1 < H && j+1 < W ) rd[i][j] = rd[i+1][j+1]+1;
        }
    }
    vector lu_to_rd(H+1, vector<int>(W+1));
    vector ru_to_ld(H+1, vector<int>(W+1));
    for( int i = 0; i < H; i++ ) {
        for( int j = 0; j < W; j++ ) {
            int t = min({ru[i][j], lu[i][j], ld[i][j], rd[i][j]});
            if( t < 1 ) continue;
            lu_to_rd[i-t][j-t]++;
            lu_to_rd[i+t+1][j+t+1]--;
            ru_to_ld[i-t][j+t]++;
            ru_to_ld[i+t+1][j-t+1]++;
        }
    }
    for( int i = 0; i < H; i++ ) {
        for( int j = 0; j < W; j++ ) {
            lu_to_rd[i+1][j+1] += lu_to_rd[i][j];
            if( j > 0 ) ru_to_ld[i+1][j-1] += ru_to_ld[i][j];
        }
    }
    vector<string> ret(H, string(W, '.'));
    for( int i = 0; i < H; i++ ) {
        for( int j = 0; j < W; j++ ) {
            if( lu_to_rd[i][j] > 0 || ru_to_ld[i][j] ) {
                ret[i][j] = '#';
            }
        }
    }
    return ret;
}

int main() {
    int H, W;
    cin >> H >> W;
    vector<string> S(H);
    for( int i = 0; i < H; i++ ) {
        cin >> S[i];
    }
    // cout << endl;
    // for( auto _dbg : solve(S) ) cout << _dbg << endl;
    cout << ( S == solve(S) ? "Yes" : "No" ) << endl;
}