H, W = map(int, input().split())
s = []
for _ in range(H):
    s.append(input())
    
Flg = "Yes"
for i in range(H-1):
    for j in range(W):
        if(s[i][j] == '#'):
            if(s[i][max(j-1, 0)] == "." and s[i][min(j+1, W-1)] == '.' and s[i+1][j] == '.'):
                Flg = "No"

print(Flg)