#include <bits/stdc++.h>
using namespace std;
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))

int H,W,c;
vector<string> m;
const int dir[][2] = {{1,0},{0,-1},{-1,0},{0,1}};

bool check(int cx, int cy, int cd){
    int x = cx, y = cy, d = cd;
    vector<string> k = m;
    int cnt = 0;
    while(cnt < c){
        int mx = x + dir[d][0];
        int my = y + dir[d][1];
        if(mx < 0 || my < 0 || mx >= W || my >= H || k[my][mx] == '#'){
            d = (d+1)%4;
            mx = x + dir[d][0];
            my = y + dir[d][1];
            if(mx < 0 || my < 0 || mx >= W || my >= H || k[my][mx] == '#'){
                return false;
            }
        }
        k[my][mx] = '#';
        cnt++;
        if(mx == cx && my == cy){
            return (c == cnt);
        }
        x = mx, y = my;
    }
}

int main(){
    cin >> H >> W;

    REP(i,H){
        string s;
        cin >> s;
        if(s.size() != W) throw;
        m.push_back(s);
        REP(x,W) if(s[x] == '.') c++;
    }
    if(c == 1) throw;

    REP(y,H) REP(x,W){
        if(m[y][x] != '.') continue;
        REP(d,4){
            if(check(x,y,d)){
                cout << "YES" << endl;
                return 0;
            }
        }
    }
    cout << "NO" << endl;
    return 0;
}