H,W = map(int,input().split())
s=[input() for _ in range(H)]

ok = True
def check(i,j,H,W,s):
    flag = False
    if (i+1) < (H-1):
        if s[i+1][j] == "#":
            flag = True
    if (i-1) >= 0:
        if s[i-1][j] == "#":
            flag = True
    if (j+1) < (W-1):
        if s[i][j+1] == "#":
            flag = True
    if (j-1) >= 0:
        if s[i][j-1] == "#":
            flag = True
    return flag

for i in range(H):
    for j in range(W):
        if s[i][j] == "#":
            ch = check(i,j,H,W,s)
            if not ch:
                ok = False
                break
    if not ok:
        break
    


if ok:
    print("Yes")
else:
    print("No")