#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
using namespace std;

#define ll         long long
#define PI         acos(-1.0)
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)

//方針
//全てのマスについて(dx, dy)移動した先に黒マスがあればOK
//全探索

int main(){
    int H, W;
    cin >> H >> W;
    vector<string> mass(H, "a");
    FOR(i, 0, H) cin >> mass[i];
    bool isPainted[H][W];
    FOR(i, 0, H) FOR(j, 0, W) isPainted[i][j] = false;
    bool check = false;
    FOR(dy, -50, 51){
        FOR(dx, -50, 51){
            if(dy==0 && dx==0) continue;
            FOR(i, 0, H) FOR(j, 0, W) isPainted[i][j] = false;
            //注目するマスをFORでまわす
            FOR(z, 0, (H-1)*W+W){
                int y = z / W;
                int x = z % W;
                if(mass[y][x]=='#' && isPainted[y][x]==false){
                    isPainted[y][x]=true;
                    if(y+dy<0 || y+dy>H || x+dx<0 || x+dx>W){
                        check = false;
                        break;
                    }
                    if(mass[y+dy][x+dx]=='#' && isPainted[y+dy][x+dx]==false){
                        isPainted[y+dy][x+dx]=true;
                        check = true;
                    }
                    else{
                        check = false;
                        break;
                    }
                }
            }
            if(check){
                cout << "YES" << endl;
                return 0;
            }
        }
    }
    cout << "NO" << endl;
}