#include <bits/stdc++.h>
using namespace std;
const int MAXN = 50 + 5;
int n, m;
char arr[MAXN][MAXN];
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%s", &arr[i]);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      if (arr[i][j] == '#') {
        for (int a = i + 1; a < n; a++) {
          if (arr[a][j] == '#') {
            int sum = 0;
            for (int b = 0; b < m; b++) {
              if (arr[i][b] == arr[a][b]) sum++;
            }
            if (sum != m) return !printf("No\n");
          }
        }
      }
    }
  }
  printf("Yes\n");
  return 0;
}
