#include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
int n,m;
char map[55][55];
int main()
{
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
        scanf("%s",map[i]+1);
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
        {
            if(map[i][j]=='#')
            {
                if(map[i-1][j]=='#'||map[i+1][j]=='#'||map[i][j-1]=='#'||map[i][j+1]=='#')continue;
                printf("No\n");return 0;
            }
        }
    printf("Yes\n");
}