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

import sys
for j in range(H):
    for i in range(W):
        if s[j][i] =='#':
            if j+1<W and i+1<H and j-1>=0 and i-1>=0:
                if (s[j+1][i]=='#' or s[j][i+1]=='#'or s[j][i-1]=='#',or s[j-1][i]=='#'):
                    continue
                if s[j+1][i]!='#' or s[j][i+1]!='#' or s[j-1][i]!='#' or s[j][i-1]!='#':
                    sys.exit()
print('Yes')
