import Foundation
 
let hw = readLine()!.componentsSeparatedByString(" ")
let h = Int(hw[0])!
let w = Int(hw[1])!
var line: [String] = []
while let s = readLine() {
    line.append(s)
}
 
let s: [[String]] = []
 
for l in line {
    let characters = l.characters.map { String($0) }
    s.append(characters)
}
 
for i in 0..<h {
    for j in 0..<w {
        if s[i][j] == "#" {
            if i - 1 > 0 {
                if s[i - 1][j] == "#" {
                    break
                }
            }
            if i + 1 <= w {
                if s[i + 1][j] == "#" {
                    break
                }
            }
            if j - 1 > 0 {
                if s[j - 1][j] == "#" {
                    break
                }
            }
            if j + 1 < h {
                if s[j + 1][j] == "#" {
                    break
                }
            }
            print("No")
            exit(0)
        }
    }
}
 
print("Yes")