#include <bits/stdc++.h>
using namespace std;
#define LL long long
#undef INT_MIN
#undef INT_MAX
#define INT_MIN -2147483648
#define INT_MAX 2147483647
#define LL_MIN -9223372036854775808
#define LL_MAX 9223372036854775807
int main(){
    int H,W;
    cin >> H >> W;
    vector<string> S;
    for(int i=0; i<H; i++){
        strint t;
        cin >> t;
        S.push_back(t);
    }
    bool flg = true;
    for(int i=0; i<H; i++){
        for(int j=0; j<W; j++){
            if(S[i][j]=='#'){
                bool tmp = false;
                if(j-1 >= 0 && S[i][j-1]=='#') tmp = true;
                if(i-1 >= 0 && S[i-1][j]=='#') tmp = true;
                if(j+1 < W && S[i][j+1]=='#') tmp = true;
                if(i+1 < H 0 && S[i+1][j]=='#') tmp = true;
                if(!tmp) flg = false;
            }
            
        }
    }
    if(flg) cout << "Yes" << endl;
    else cout << "No" << endl;
    
    return 0;
}