#include <bits/stdc++.h>
using namespace std;
int n, m;
char bd[51][51], _;
bool ok, same, diff;
int main() {
  scanf("%d%d%c", &n, &m, &_);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) scanf("%c", &bd[i][j]);
    scanf("%c", &_);
  }
  ok = true;
  for (int i = 0; i < n - 1 && ok; i++)
    for (int j = i + 1; j < n && ok; j++) {
      same = false;
      diff = false;
      for (int k = 0; k < m; k++) {
        if (bd[i][k] == bd[j][k] && bd[i][k] == '#')
          same = true;
        else if (bd[i][k] == '#' || bd[j][k] == '#')
          diff = true;
      }
      if (same && diff) ok = false;
    }
  printf(ok ? "Yes\n" : "No\n");
  return 0;
}
