import sys
input = sys.stdin.readline
H,W=map(int,input().split())
s=[]
s0=""
for i in range(W+2):
    s0+="."
s.append(s0)
for i in range(H):
    ss="."
    ss+=input().strip()+"."
    s.append(ss)
s.append(s0)
#print(s)
flg=True
for h in range(H+1):
    for w in range(W+1):
        if s[h][w]=="#":
            flg=False
            for i in [1,-1]:
                if s[h+i][w]=="#":
                    flg=True
            for j in [1,-1]:
                if s[h][w+j]=="#":
                    flg=True
print("Yes" if flg else "No")
