测试点：点我

code：

#include <bits/stdc++.h>
using namespace std;
int x[] = {0, 0, 0, 1, -1}, y[] = {0, 1, -1, 0, 0};
char a[110][110];
int n,m;
int flag=0;
void dfs(int x1, int y1)
{
    for (int i = 1; i <= 4; i++)
    {
        int x2 = x1 + x[i], y2 = y1 + y[i];
        if (x2 >= 1 || x2 <= n || y2 >= 1 || y2 <= m)
        {
            if(x2==n && y2==m)
            {
                flag=1;
                return;
            }
            else if(x2>=1&&x2<=n&&y2>=1&&y2<=m&&a[x2][y2]=='.')
            {
                dfs(x2, y2);
            }
        }
    }
}
int main()
{
    int x1, y1;
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= m; j++)
        {
            cin >> a[i][j];
        }
    }
    dfs(1, 1);
    if(flag)
        cout<<"Yes"<<endl;
    else
        cout<<"No"<<endl;
    return 0;
}