//#define _GLIBCXX_DEBUG
#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef long double ld;

#define mk make_pair
#define inb push_back
#define X first
#define Y second
#define all(v) v.begin(), v.end()
#define sqr(x) (x) * (x)
#define TIME 1.0 * clock() / CLOCKS_PER_SEC
#define y1 AYDARBOG
//continue break pop_back return size_t

int solve();

int main()
{
    //ios_base::sync_with_stdio(0);
    //cin.tie(0);
#define TASK "html"
#ifndef _DEBUG
    //freopen(TASK".in", "r", stdin), freopen(TASK".out", "w", stdout);
#endif
    solve();
#ifdef _DEBUG
    fprintf(stderr, "\nTIME: %.3f\n", TIME);
#endif
}

const int BUFSZ = (int)1e5 + 7;
char buff[BUFSZ];
string get_str()
{
    scanf(" %s", buff);
    return string(buff);
}

struct edge
{
    int to, f, c;
    edge() {};
    edge(int to, int f, int c) : to(to), f(f), c(c) {};
};

const int INF = (int)1e9 + 7;

struct Dinic
{
    int n;
    vector<edge> e;
    vector<vi> g;
    vi p, d;
    int s, t;
    Dinic() {};
    Dinic(int _n)
    {
        n = _n;
        g.resize(n);
        s = 0, t = n - 1;
    }
    void add_edge(int x, int y, int c = 1)
    {
        g[x].inb(e.size());
        e.inb(edge(y, 0, c));
        g[y].inb(e.size());
        e.inb(edge(x, 0, 0));
    }
    int bfs()
    {
        queue<int> q;
        d.assign(n, INF);
        d[s] = 0;
        int ans = 0;
        q.push(s);
        while (!q.empty())
        {
            int u = q.front();
            q.pop();
            for (int ne : g[u])
            {
                int to = e[ne].to;
                int f = e[ne].f;
                int c = e[ne].c;
                if (d[to] != INF || f >= c)
                    continue;
                ans |= (to == t);
                d[to] = d[u] + 1;
                q.push(to);
            }
        }
        return ans;
    }
    int dfs(int u, int minc)
    {
        if (u == t || !minc)
            return minc;
        for (size_t i = p[u]; i < g[u].size(); ++i)
        {
            int ne = g[u][i];
            int to = e[ne].to;
            int f = e[ne].f;
            int c = e[ne].c;
            if (d[u] + 1 != d[to])
                continue;
            int delta = dfs(to, min(minc, c - f));
            if (delta)
            {
                e[ne].f += delta;
                e[ne ^ 1].f -= delta;
                return delta;
            }
            ++p[u];
        }
        return 0;
    }
    int getMaxFlow()
    {
        int ans = 0;
        while (bfs())
        {
            p.assign(n, 0);
            int flow = dfs(s, INF);
            while (flow)
            {
                ans += flow;
                flow = dfs(s, INF);
            }
        }
        return ans;
    }
};

int solve()
{
    int n, m;
    scanf("%d %d", &n, &m);
    Dinic G(n * m + 2);
    char a[n][m + 1];
    for (int i = 0; i < n; ++i)
    {
        scanf(" %s", a[i]);
    }
    int fr = n * m;
    for (int i = 0; i < n; ++i)
    {
        for (int j = 0; j < m; ++j)
        {
            if (a[i][j] == '#')
            {
                --fr;
                continue;
            }
            if ((i + j) & 1)
            {
                G.add_edge(i * m + j, n * m + 1);
            }
            else
            {
                G.add_edge(0, i * m + j);
            }
        }
    }
    vi dx = { -1, 0, 1, 0 };
    vi dy = { 0, -1, 0, 1 };
    for (int x = 0; x < n; ++x)
    {
        for (int y = x & 1; y < m; y += 2)
        {
            if (a[x][y] == '#')
                continue;
            for (int id = 0; id < 4; ++id)
            {
                int nx = x + dx[id];
                int ny = y + dy[id];
                if (nx < 0 || nx >= n || ny < 0 || ny >= m || a[nx][ny] == '#')
                    continue;
                G.add_edge(x * m + y, nx * m + ny);
            }
        }
    }
    int mxflow = G.getMaxFlow();
    puts((mxflow * 2 == fr) ? "Yes" : "No");
    return 0;
}
close