#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <queue>
using namespace std;

//conversion
//------------------------------------------
inline int toInt(string s)
{
    int v;
    istringstream sin(s);
    sin >> v;
    return v;
}
template <class T>
inline string toString(T x)
{
    ostringstream sout;
    sout << x;
    return sout.str();
}

//math
//-------------------------------------------
template <class T>
inline T sqr(T x) { return x * x; }

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

//container util
//------------------------------------------
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i, c) for (typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort((c).begin(), (c).end())

//repetition
//------------------------------------------
#define FOR(i, a, b) for (int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI = acos(-1.0);

//clear memory
#define CLR(a) memset((a), 0, sizeof(a))

//debug
#define dump(x) cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" \
                      << " " << __FILE__ << endl;

const int MAX_H = 50, MAX_W = 50;
int H, W;
char S[MAX_H][MAX_W];
char board[MAX_H][MAX_W];
//https://yukicoder.me/problems/no/179/editorial
int main()
{
    cin >> H >> W;
    bool allwhite = true;
    for (int h = 0; h < H; h++)
    {
        for (int w = 0; w < W; w++)
        {
            cin >> S[h][w];
            if (S[h][w] != '.')
            {
                allwhite = false;
            }
        }
    }
    if (allwhite)
    {
        cout << "NO" << endl;
        exit(0);
    }
    memcpy(board, S, sizeof(board));
    

    //右だけに移動
    for (int dw = 1; dw < W; dw++)
    {                                    //djは移動量
        memcpy(board, S, sizeof(board)); //盤の初期化
        for (int h = 0; h < H; h++)
        {
            for (int w = 0; w < W; w++)
            {
                if (board[h][w] == '#')
                {
                    board[h][w] = 'R';
                    if (w + dw >= W || board[h][w + dw] != '#')
                    {
                        goto NEXTCASE;
                    }
                    board[h][w + dw] = 'B';
                }
            }
        }
        for (int h = 0; h < H; h++)
        {
            for (int w = 0; w < W; w++)
            {
                if (board[h][w] == '#')
                {
                    goto NEXTCASE;
                }
            }
        }
        cout << "YES" << endl;
        // for(int h=0;h<H;h++){
        //     for(int w=0;w<W;w++){
        //         cerr<<board[h][w];
        //     }
        //     cerr<<endl;
        // }
        exit(0);
    NEXTCASE:;
    }

    //右下に移動
    for (int dh = 1; dh < H; dh++)
    {
        for (int dw = -W + 1; dw < W; dw++)
        {                                    //djは移動量
            memcpy(board, S, sizeof(board)); //盤の初期化
            for (int h = 0; h < H; h++)
            {
                for (int w = 0; w < W; w++)
                {
                    if (board[h][w] == '#')
                    {
                        board[h][w] = 'R';
                        if (w + dw >= W ||h+dh>=H||w+dw<0 ||  board[h+dh][w + dw] != '#')
                        {
                            goto NEXTCASE2;
                        }
                        board[h+dh][w + dw] = 'B';
                    }
                }
            }
            for (int h = 0; h < H; h++)
            {
                for (int w = 0; w < W; w++)
                {
                    if (board[h][w] == '#')
                    {
                        goto NEXTCASE2;
                    }
                }
            }
            cout << "YES" << endl;
            // for(int h=0;h<H;h++){
            //     for(int w=0;w<W;w++){
            //         cerr<<board[h][w];
            //     }
            //     cerr<<endl;
            // }
            exit(0);
        NEXTCASE2:;
        }
    }

    cout<<"NO"<<endl;
    exit(0);
}