h,w = map(int,input().split())
s = [['.']*(w) for i in range(h+2)]

for i in range(h):
    s[i+1] = [x for x in input()]

for i in range(h+2):
    s[i].insert(w,".")
    s[i].insert(0,".")
    
for i in range(h+2):
    for j in range(w+2):
        if s[i][j] == "#":
            if s[i-1][j]=="#" or s[i+1][j]=="#" or s[i][j-1]=="#" or s[i][j+1]=="#":
                pass
            else:
                print("No")
                break
print("Yes")
