H,W=map(int,input().split())
S=[]
for i in range(H):
    s=input()
    S.append(s)
for i in range(H):
    for j in range(W):
        if S[j][i]==".":
            continue
        l=[(j-1,i),(j+1,i),(j,i+1),(j,i-1)]
        koritu=True
        for y,x in l:
            if 0<=y<=H-1 and  0<=x<=W-1:
                koritu=koritu and S[y][x]=="."
        if koritu:
            print("No")
            quit()
print("Yes")
