#!/usr/bin/env python3
import sys

YES = "Yes"  # type: str
NO = "No"  # type: str

def get_s(i,j,s,H,W):
    if 0 <= i < H and 0 <= j < W:
        return s[i][j]
    else:
        return "."

def solve(H: int, W: int, s: "List[str]"):


    for i in range(H):
        for j in range(W):
            if s[i][j] == "#":
                if get_s(i+1,j,s,H,W) == "." \
                        and get_s(i-1,j,s,H,W) == "."\
                        and get_s(i,j+1,s,H,W) == "."\
                        and get_s(i,j-1,s,H,W) == ".":
                            print(NO)
                            return

    print(YES)
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    H = int(next(tokens))  # type: int
    W = int(next(tokens))  # type: int
    s = [ next(tokens) for _ in range(W) ]  # type: "List[str]"
    solve(H, W, s)

if __name__ == '__main__':
    main()
