H, W = map(int, input().split())
 
C = ["."*(W+2)]
for k in range(H):
    C.append("."+input()+".")
C.append("."*(W+2))
 
for k,l in zip(range(1,W+1),range(1,H+1)):
    if C[l][k]=="#":
        if C[l+1][k]=="#" or C[l-1][k]=="#" or C[l][k+1]=="#" or C[l][k-1]=="#":
            pass
        else:
            print("No")
            exit()
print("Yes")