#include <bits/stdc++.h>
using namespace std;
bitset<55> dic[55];
char grid[55][55];
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) {
    scanf("%s", grid[i]);
    for (int j = 0; j < m; j++) {
      if (grid[i][j] == '#')
        dic[i][j] = true;
      else
        dic[i][j] = false;
    }
  }
  bool ok = true;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++)
      if (dic[i] != dic[j] && (dic[i] | dic[j]) != (dic[i] ^ dic[j]))
        ok = false;
  }
  if (ok)
    puts("Yes");
  else
    puts("No");
  return 0;
}
