H,W=map(int,input().split())

xy=((-1,0),(1,0),(0,-1),(0,1))
S=[]
S.append("."*(W+2))
for i in range(H):
    S.append("."+input()+".")

S.append("."*(W+2))

for i in range(1,H+1):
    for j in range(1,W+1):
        if S[i][j]==".":
            ans=True
            continue
        ans=False
        for x,y in xy:
            if S[i+x][j+y]=="#":
                ans=True
                break

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