import numpy as np
h,w=map(int,input().split())
s=list(input() for i in range(h))
flag=False
for i in range(h):
    for j in range(w):
        if(s[i][j]=="#"):
            flag=False
            for k in[-1,1]:
                if(i+k<h and 0<i+k and s[i+k][j]=="#"):
                    flag=True
                if(j+k<w and 0<j+k and s[i][j+k]=="#"):
                    flag=True

if(flag==True):
    print("Yes")
else:
    print("No")
