#include <bits/stdc++.h>
#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
// VAR(int, x);
#define VAR(type, ...)type __VA_ARGS__;Scan(__VA_ARGS__);
template<typename T> void Scan(T& t){std::cin >> t;}
template<typename First,typename...Rest>void Scan(First& first,Rest&...rest){std::cin>>first;Scan(rest...);}
#define OUT(d) std::cout<<(d);
#define FOUT(n, d) std::cout<<std::fixed<<std::setprecision(n)<<(d);
#define SOUT(n, d) std::cout<<std::setw(n)<<(d);
#define SP std::cout<<" ";
#define TAB std::cout<<"\t";
#define BR std::cout<<"\n";
#define ENDL std::cout<<std::endl;
#define FLUSH std::cout<<std::flush;
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& r:c)for(auto& i:r)std::cin>>i;
#define ALL(a) (a).begin(),(a).end()
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define RFOR(i, a, b) for(int i=(b)-1;i>=(a);--i)
#define REP(i, n) for(int i=0;i<(n);++i)
#define RREP(i, n) for(int i=(n)-1;i>=0;--i)
#define PAIR std::pair<int, int>
#define IN(a0, y, a1, b0, x, b1) (a0<=y && y<a1 && b0<=x && x<b1)
#define SHOW(d) {std::cout << #d << "\t:" << d << "\n";}
#define SHOWVECTOR(v) {std::cout << #v << "\t:";for(auto i : v){std::cout << i << " ";}std::cout << "\n";}
#define SHOWVECTOR2(v) {std::cout << #v << "\t:\n";for(auto i : v){for(auto j : i){std::cout << j << " ";}std::cout << "\n";}}
#define SHOWPAIRVECTOR(v) {for(auto i:v){std::cout<<'('<<i.first<<", "<<i.second<<") ";}std::cout<<"\n";}
//#define int ll
using ll = long long;
const int INF = 1<<30;

signed main(){
    INIT;
    VAR(int, h, w);
    VEC(std::string, s, h);
    bool ok = true;
    REP(i, h){
        REP(j, w){
            if(s[i][j]=='#') ok = false;
        }
    }
    if(ok){
        OUT("NO")BR;
        return 0;
    }
    FOR(i, -h, h+1){
        FOR(j, -w, w+1){
            if(i==0 && j==0) continue;
            std::vector<std::vector<bool>> check(h, std::vector<bool>(w, false));
            bool flag = true;
            REP(k, h){
                REP(l, w){
                    if(s[k][l]=='#' && !check[k][l]){
                        check[k][l] = true;
                        if(!IN(0, i+k, h, 0, j+l, w)){
                            flag = false;
                            break;
                        }
                        if(s[i+k][j+l]=='#' && !check[i+k][j+l]){
                            check[i+k][j+l] = true;
                        }else{
                            flag = false;
                            break;
                        }
                    }
                }
            }
            if(flag) ok = true;
        }
    }
    OUT(ok?"YES":"NO")BR;       
    return 0;
}