"use strict";
function main(input) {
  const args = input.split('\n');
  const size = input.split(' ');
  const h = parseInt(size[0], 10);
  const w = parseInt(size[1], 10);
  const s = [];

  for (let i = 0; i < h; i += 1) {
    s[i] = [];
    let input = args[i];
    for (let j = 0; j < w; j += 1) {
      s[i][j] = input[j];
    }
  }
  s[-1] = [];
  s[h] = [];

  for (let i = 0; i < h; i += 1) {
    for (let j = 0; j < w; j += 1) {
      if (s[i][j] === '#') {
        if (s[i-1][j] !== '#' && s[i+1][j] !== '#' &&
            s[i][j-1] !== '#' && s[i][j+1] !== '#') {
          console.log('No');
          return;
        }
      }
    }
  }
  console.log('Yes');
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));
