#include<iostream>
#include<cmath>
using namespace std;
char map[1100][1100];
bool vis[1100][1100];
int dx[5] = {0,0,0,1,-1},dy[5] = {0,1,-1,0,0};
int ans,n,m;
int dfs(int x,int y){
	if(x == n and y == m){
		return 1;
	}
	if(map[1][1] == '#'){
		return 0;
	}
	for(int i = 1;i <= 4;i ++){
		int n_dx = x + dx[i];
		int n_dy = y + dy[i];
		if(n_dx > 1 and n_dx <= n and n_dy > 1 and n_dy <= m){
			if(map[n_dx][n_dy] == '.' and vis[n_dx][n_dy] == 0){
                vis[n_dx][n_dy] = 1;
				dfs(n_dx,n_dy);
			}
		}
	}
}
int main(){
	cin>>n>>m;
	for(int i = 1;i <= n;i ++){
		for(int j = 1;j <= m;j ++){
			cin>>map[i][j];
		}
	}
    dfs(1,1);
	if(vis[n][m] == 0){
		cout<<"Yes";
	}
	else{
		cout<<"No";
	}
	return 0;
}

在线等，急！