import sys
h, w = (int(i) for i in input().split())
s =[list(input()) for i in range(h)]
flags = []
for i in range(0,h):
    flags.append([0 for i in range(w)])

for i in range(0,h):
    for j in range(0,w-1):
        if s[i][j]=='#' and s[i][j+1]=='#':
            flags[i][j]=1
            flags[i][j+1]=1

for i in range(0,w):
    for j in range(0,h-1):
        if s[j][i]=='#' and s[j+1][i]=='#':
            flags[j][i]=1
            flags[j+1][i]=1

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

print("Yes")
