h,w=map(int,input().split())
t=[list(input())for i in range(h)]
cnt=0#"#"の数
for i in range(h):
    for j in range(w):
        if t[i][j]=="#":
            cnt+=1
dx=[1,0-1,0,0]
dy=[0,-1,0,1,0]
cout=0
for i in range(h):
    for j in range(w):
        if t[i][j]=="#":
            for k in range(4):
                x_p=i+dx[k]
                y_p=j+dy[k]
                if 0<=x_p and x_p<h and 0<=y_p and y_p<w and t[x_p][y_p]=="#":
                    cout+=1
                    t[x_p][y_p]="."
            t[i][j]="."
if cout==cnt:
    print("Yes")
else:
    print("No")
