import sys
h, w = map(int, input().split())
s = [list(input()) for _ in range(h)]
hantei = [[0 for _ in range(h)] for _ in range(w)]
for i in range(h):
    for j in range(w):
        if s[i][j] == "#":
            if i < h-1:
                if s[i+1][j] == "#":
                    hantei[i][j] = 1
                    hantei[i+1][j] = 1
            if j < w-1:
                if s[i][j+1] == "#":
                    hantei[i][j] = 1
                    hantei[i][j+1] = 1

for i in range(h):
    for j in range(w):
        if s[i][j] == "#":
            if hantei[i][j] == 0:
                print("No")
                sys.exit()

print("Yes")