h,w = map(int,input().split())
s = [input() for _ in range(h)]
ans = 'Yes'
for i in range(h):
    f = False
    for j in range(w):
        if s[i][j]=='#':
            if i>=0 and s[i-1][j]=='#': f=True
            if i<h-1 and s[i+1][j]=='#': f=True
            if j>=0 and s[i][j-1]=='#': f=True
            if j<w-1 and s[i][j+1]=='#': f=True
            if not f:
                ans = 'No'
print(ans)