#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

const int DY[] = {-1,0,1,0,-1,-1,1,1};
const int DX[] = {0,1,0,-1,-1,1,-1,1};

char A[110][110];
int vis[110][110], N, M, cnt[110][110];

bool f(){
    queue<pii> q;
    q.push(mp(0, 0));
    while(sz(q)){
        int y, x;
        tie(y, x) = q.front(); q.pop();
        if(vis[y][x]++)continue;
        int ny, nx;
        rep(i, 4){
            ny = y + DY[i], nx = x + DX[i];
            if(ny >= 0 && nx >= 0 && ny < N&&nx < M && A[ny][nx]=='#' && !vis[ny][nx]){
                q.push(mp(ny, nx));
            }
        }
        rep(i, 8){
            ny = y + DY[i], nx = x + DX[i];
            if(ny >= 0 && nx >= 0 && ny < N&&nx < M && A[ny][nx] == '.'){
                vis[ny][nx] = 1;
                cnt[ny][nx]++;
            }
        }
    }
    rep(i, N)rep(j, M)if(A[i][j] == '.' && !vis[i][j])return 0;
    int l = 0, r = 0;
    rep(i, N)rep(j, M)if(A[i][j]=='.'){
        if(cnt[i][j] == 1)r++;
        if(cnt[i][j] >= 4)l++;
    }
    return (l == 4 && r == 0) || (l == 5 && r == 1);
}

int main(){
    MEM(A, '#');
    cin >> N >> M;
    rep(i, N){
        scanf("%s", A[i+1] + 1);
        A[i+1][M+1] = '#';
    }
    N += 2; M += 2;
    puts(f() ? "YES" : "NO");
}