'use strict'

function main(s) {

  s = s.split('\n');
  const h = Number(s[0].split(' ')[0]);
  const w = Number(s[0].split(' ')[0]);
  const table = s.slice(1, -1).map(x => x.split(''));

  let ans = 'Yes';
  for (let i = 0; i < h; i++) {
    for (let j = 0; j < w; j++) {
      if (table[i][j] === '.') continue;

      if (i !== 0) { // top
        if (table[i - 1][j] === '#') continue;
      }
      if (i !== (h - 1)) { // down
        if (table[i + 1][j] === '#') continue;
      }
      if (j !== (w - 1)) { // right
        if (table[i][j + 1] === '#') continue;
      }
      if (j !== 0) { // left
        if (table[i][j - 1] === '#') continue;
      }

      ans = 'No';
    }
  }

  console.log(ans);
}

main(require("fs").readFileSync("/dev/stdin", "utf8"));
