#include <bits/stdc++.h>
using namespace std;
int n, m;
char maze[105][105];
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; i++) {
    scanf("%s", maze[i]);
  }
  for (int i = 0; i < n; i++) {
    for (int j = i + 1; j < n; j++) {
      if (strcmp(maze[i], maze[j])) {
        for (int k = 0; k < m; k++) {
          if (maze[i][k] == maze[j][k] && maze[i][k] == '#') {
            printf("No\n");
            return 0;
          }
        }
      }
    }
  }
  printf("Yes\n");
  return 0;
}
