import numpy as np
h,w=map(int,input().split())
s=list(input() for i in range(h))
flag=False
ans="Yes"
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
                    break
                if(j+k<w and 0<=j+k and s[i][j+k]=="#"):
                    flag=True
                    break
                if(flag==False):
                    ans="No"
                    break

        
print(ans)        