#include <algorithm>
#include <iostream>
#include <cstdio>
#include <map>
#include <numeric>
#include <cmath>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <complex>
#include <string.h>
#include <unordered_set>
#include <unordered_map>
#include <bitset>
#include <iomanip>
#include <sys/time.h>
#include <random>
using namespace std;

#define endl '\n'
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define UNIQ(v) (v).erase(unique((v).begin(), (v).end()), (v).end())

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;
typedef complex<double> comp;
typedef vector< vector<ld> > matrix;
struct pairhash {
public:
    template<typename T, typename U>
    size_t operator()(const pair<T, U> &x) const {
	size_t seed = hash<T>()(x.first);
	return hash<U>()(x.second) + 0x9e3779b9 + (seed<<6) + (seed>>2);
    }
};
const int inf = 1e9 + 9;
const ll mod = 1e9 + 7;
const double eps = 1e-8;
const double pi = acos(-1);

int n, m;
string a[110];

int dx[4] = {0, 1, 0,-1};
int dy[4] = {1, 0,-1, 0};

bool used[100][100];
int cnt;
int sx, sy;

bool check(int p, int q, int d, int c) {
    if (p == sy && q == sx && used[p][q] && c == cnt) return true;
    used[p][q] = true;
    int y = p + dy[d], x = q + dx[d];
    if (0 <= y && y < n && 0 <= x && x < m && a[y][x] == '.' && (!used[y][x]||(y==sy&&x==sx))) {
        return check(y, x, d, c+1);
    }
    d = (d + 1) % 4;
    y = p + dy[d]; x = q + dx[d];
    if (0 <= y && y < n && 0 <= x && x < m && a[y][x] == '.' && (!used[y][x]||(y==sy&&x==sx))) {
        return check(y, x, d, c+1);
    }
    return false;
}

bool solve() {
    cnt = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            cnt += (a[i][j] == '.');
    
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (a[i][j] == '.') {
                for (int d = 0; d < 4; d++) {
                    memset(used, false, sizeof(used));
                    sy = i; sx = j;
                    if (check(i, j, d, 0)) return true;
                }
            }
        }
    }
    return false;
}

void input() {
    cin >> n >> m;
    for (int i = 0; i < n; i++) cin >> a[i];
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);

    input();
    cout << (solve()?"YES":"NO") << endl;
}