#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

int dy[] = {-1, 0, 1, 0};
int dx[] = {0, -1, 0, 1};

bool solve(vector<string> s, int n, int sy, int sx, int d)
{
    int y = sy;
    int x = sx;
    int cnt = 0;
    for(int i=0; i<n; ++i){
        int k = 0;
        int d2, y2, x2;
        while(k < 3){
            d2 = (d + 3 + k) % 4;
            y2 = y + dy[d2];
            x2 = x + dx[d2];
            if(s[y2][x2] == '.')
                break;
            ++ k;
        }
        if(k == 3)
            return false;

        if(k == 0){
            ++ cnt;
            if(cnt > 1)
                return false;
        }
        d = d2;
        y = y2;
        x = x2;
        s[y][x] = '#';
    }

    return y == sy && x == sx;
}

int main()
{
    int h, w;
    cin >> h >> w;

    vector<string> s(h+2, string(w+2, '#'));
    int n = 0;
    int sy, sx;
    for(int y=1; y<=h; ++y){
        for(int x=1; x<=w; ++x){
            cin >> s[y][x];
            if(s[y][x] == '.'){
                ++ n;
                sy = y;
                sx = x;
            }
        }
    }

    bool ok = false;
    for(int i=0; i<4; ++i)
        ok |= solve(s, n, sy, sx, i);
    if(ok)
        cout << "YES" << endl;
    else
        cout << "NO" << endl;

    return 0;
}