// Enjoy your stay.

#include <bits/stdc++.h>

#define EPS 1e-9
#define INF 1070000000LL
#define MOD 1000000007LL
#define fir first
#define foreach(it,X) for(auto it=(X).begin();it!=(X).end();it++)
#define ite iterator
#define mp make_pair
#define mt make_tuple
#define rep(i,n) rep2(i,0,n)
#define rep2(i,m,n) for(int i=m;i<(n);i++)
#define pb push_back
#define sec second
#define sz(x) ((int)(x).size())

using namespace std;

typedef istringstream iss;
typedef long long ll;
typedef pair<ll,ll> pi;
typedef stringstream sst;
typedef vector<ll> vi;

int N,M;
char c[111][111];
int dy[] = {0,-1,0,1};
int dx[] = {1,0,-1,0};
int v[111][111];

int main(){
	cin.tie(0);
	ios_base::sync_with_stdio(0);
	
	cin>>N>>M;
	rep2(i,1,N+1)cin>>c[i]+1;
	rep(i,N+2)rep(j,M+2){
		if(i == 0 || i == N+1 || j == 0 || j == M+1){
			c[i][j] = '#';
		}
	}
	int dot = 0;
	rep(i,N+2)rep(j,M+2) dot += c[i][j] == '.';
	if(dot > 2 * N + 2 * M - 4) return cout<<"NO"<<endl,0;
	rep(sy,N+2)rep(sx,M+2)if(c[sy][sx] == '.'){
		rep(sd,4){
			int y = sy, x = sx, d = sd, count = 1;
			memset(v,0,sizeof(v));
			v[sy][sx]++;
			while(1){
				if(v[y][x] == 2){
					if(count == dot + 1){
						return cout<<"YES"<<endl,0;
					}
					else break;
				}
				if(c[y + dy[d]][x + dx[d]] == '.'){
					y += dy[d], x += dx[d], count++, v[y][x]++;
				}
				else{
					d = (d + 1) % 4;
					if(c[y + dy[d]][x + dx[d]] == '.'){
						y += dy[d], x += dx[d], count++, v[y][x]++;
					}
					else break;
				}
			}
		}
	}
	cout<<"NO"<<endl;
}