nums = list(map(int, input().split()))
H=nums[0]
W=nums[1]
Strings=[]
for k in range(H):
    Strings.append(input())
c=0
for i in range(H):
    list(Strings[i])
    for j in range(1, W):
        if Strings[i][j]=="#" and Strings[i][j-1]=="#":
            c=1
            break
for l in range(W):
    for m in range(1,H):
        if Strings[m][l]=="#" and Strings[m-1][l]=="#":
            c=1
            break
if c==1:
    print("Yes") 
else:
    print("No")