#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
#define dame { puts("-1"); return 0;}
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    int h,w; cin >> h >> w;
    string s[h]; rep(i,h)cin >> s[i];
    rep(i,h){
        rep(j,w){
            if(i==0&&j==0)continue;
            int a[h][w];
            rep(x,h){
                rep(y,w){
                    if(s[x][y] == '.')a[x][y] = 0;
                    else a[x][y] = 1;
                }
            }
            int f = 0;
            int blank = 0;
            rep(x,h){
                rep(y,w){
                    if(a[x][y] == 1){
                        blank = 1;
                        if(x+i>=h || y+j>=w){
                            f = 1;
                            break;
                        }else{
                            if(a[x+i][y+j] == 1){
                                a[x][y] = 2;
                                a[x+i][y+j] = 2;
                            }else{
                                f = 1;
                                break;
                            }
                        }
                    }
                }
                if(f == 1)break;
            }
            if(f == 0 && blank){
                cout << "YES" << endl;
                return 0;
            }
        }
    }

    rep(i,h){
        rep(j,w){
            if(i==0&&j==0)continue;
            int a[h][w];
            rep(x,h){
                rep(y,w){
                    if(s[x][y] == '.')a[x][y] = 0;
                    else a[x][y] = 1;
                }
            }
            int f = 0;
            int blank = 0;
            rep(x,h){
                rep(y,w){
                    if(a[x][y] == 1){
                        blank = 1;
                        if(x+i>=h || y-j<0){
                            f = 1;
                            break;
                        }else{
                            if(a[x+i][y-j] == 1){
                                a[x][y] = 2;
                                a[x+i][y-j] = 2;
                            }else{
                                f = 1;
                                break;
                            }
                        }
                    }
                }
                if(f == 1)break;
            }
            if(f == 0 && blank){
                cout << "YES" << endl;
                return 0;
            }
        }
    }

    cout << "NO" << endl;
    return 0;
}