h, w = map(int, input().split())

s = [[]*w]*h
dp = [[0]*w]*h
can = 1
for i in range(h):
    s[i] = input()

for i in range(h):
    for j in range(w):
        if(s[i][j] == "#"):
            if(i != h-1 and s[i+1][j] == "#"):
                dp[i][j] = 1
                dp[i+1][j] = 1
            if(j != w-1 and s[i][j+1] == "#"):
                dp[i][j] = 1
                dp[i][j+1] = 1
            if(dp[i][j] == 0):
                can = 0

print("Yes" if can == 1 else "No")
