#include <bits/stdc++.h>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
#endif
typedef long long  ll;
typedef pair<int,int> pii; typedef pair<ll,ll> pll;
const int INF = 1e9; const long long LINF = 1e18;
const int MOD = 998244353; const int MOD1 = 1e9+7;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(x) x.begin(), x.end()
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
void yorn(bool ans){cout << (ans?"Yes":"No") << endl; return;}

int main(){
    int h,w; cin >> h >> w;
    vector<string> g(h); rep(i,h) cin >> g.at(i);

    bool ans = false;
    int sy=INF,sx=INF;
    bool d = false;
    rep(i,h){
        rep(j,w){
            if(g.at(i).at(j)=='#'){
                sy = i; sx = j;
                g.at(i).at(j) = 'R';
                d = true;
            }
            if(d) break;
        }
        if(d) break;
    }
    if(!d){cout << "YES"<<endl; return 0;}
    //cout << "(sy,sx)=("<<sy<<','<<sx<<')'<<endl;
    for(int i=sy;i<h;i++){
        for(int j=0;j<w;j++){
            if(i==sy && j<=sx) continue;
            if(g.at(i).at(j)=='#'){
                //cout << i << ' ' << j << endl;
                auto gg = g;
                gg.at(i).at(j) = 'B';
                int dy = i-sy, dx = j-sx;
                bool ok = true;
                for(int ii=sy;ii<h;ii++){
                    for(int jj=0;jj<w;jj++){
                        if(ii==sy && jj<=sy) continue;
                        if(gg.at(ii).at(jj)=='#'){
                            gg.at(ii).at(jj) = 'R';
                            if(ii==h-1&&jj==w-1) ok = false;
                            if(0<=ii+dy&&ii+dy<h && 0<=jj+dx&&jj+dx<w && gg.at(ii+dy).at(jj+dx)=='#'){
                                gg.at(ii+dy).at(jj+dx) = 'B';
                            }
                            else ok = false;
                        }
                        if(!ok) break;
                    }
                    if(!ok) break;
                }
                if(ok){
                    //cout <<99999<< endl;
                    ans = true;
                }
                //else cout << i << ' ' << j << endl;
            }
        }
    }

    cout << (ans?"YES":"NO") << endl;
}