#include <bits/stdc++.h>
using namespace std;
int n, m;
char gird[64][64];
set<long long int> set_of_cols;
int main(void) {
  int i, j;
  scanf("%d%d", &n, &m);
  for (i = 0; i < n; ++i) scanf("%s", gird[i]);
  for (i = 0; i < n; ++i) {
    long long int id = 0;
    for (j = 0; j < m; ++j) {
      id <<= 1;
      id |= ('#' == gird[i][j]) ? 1 : 0;
    }
    for (auto have : set_of_cols) {
      if (have != id && ((have & id) != 0)) {
        puts("No");
        return 0;
      }
    }
    set_of_cols.insert(id);
  }
  puts("Yes");
  return 0;
}
