#include <bits/stdc++.h>
// #include <boost/multiprecision/cpp_int.hpp>
using namespace std;
// using bigint = boost::multiprecision::cpp_int;

template <typename T> using min_priority_queue = priority_queue<T,vector<T>,greater<T>>;

random_device seed_gen;
mt19937 engine(seed_gen());

int64_t get_time_ns(){
    struct::timespec t;
    clock_gettime(CLOCK_MONOTONIC, &t);
    return t.tv_sec * int64_t(1'000'000'000) + t.tv_nsec;
}

bool solve() {
    int h, w;
    cin >> h >> w;
    vector<string> S(h);
    for(auto &s : S) cin >> s;

    int cnt = 0;
    for(auto &s : S) for(auto &c : s) if(c == '#') cnt++;

    if(cnt == 0 || cnt % 2 != 0) return false;

    for(int di = 0; di < h; di++) {
        for(int dj = -w; dj < w; dj++) {
            if(di == 0 && dj == 0) continue;
            auto T = S;
            for(int i = 0; i < h; i++) {
                for(int j = 0; j < w; j++) {
                    int ii = i + di;
                    int jj = j + dj;
                    if(ii < 0 || h <= ii || jj < 0 || w <= jj) continue;
                    if(T[i][j] == '#' && T[ii][jj] == '#') {
                        T[i][j] = 'R';
                        T[ii][jj] = 'B';
                    }
                }
            }

            bool b = true;
            for(int i = 0; i < h; i++) {
                for(int j = 0; j < w; j++) {
                    if(T[i][j] == '#') b = false;
                }
            }

            if(b) return b;

            if(0) {
                cout << di << " " << dj << endl;
                for(auto s : T) cout << s << endl;
            }
        }
    }

    return false;
}

int main() {
    bool ans = solve();
    if(ans) cout << "YES" << endl;
    else cout << "NO" << endl;
    return 0;
}