H,W = map(int,input().split())
s = [["."] *(W+2)]+[["."]+list(input())+["."] for _ in range(W)]+[["."] *(W+2)]
#print(*s, sep="\n")
for i in range(1,H+1):
    for j in range(1,W+1):
        if s[i][j] == "#":
            if s[i-1][j]=="." and s[i][j-1]=="." and s[i+1][j]=="." and s[i][j+1]==".":
                print("No")
                exit()
print("Yes")
