#include <bits/stdc++.h>
char str[55][55];
int main(void) {
  int n, m, i, j, x, y;
  scanf("%d%d", &n, &m);
  for (i = 1; i <= n; i++) scanf("%s", str[i] + 1);
  for (i = 1; i <= n; i++) {
    for (j = 1; j <= m; j++) {
      if (str[i][j] == '.') continue;
      for (x = 1; x <= n; x++) {
        for (y = 1; y <= n; y++) {
          if (str[x][y] == '.' || i == x || j == y) continue;
          if (str[i][y] == '#' && str[x][j] == '.' ||
              str[i][y] == '.' && str[x][j] == '#') {
            printf("No\n");
            return 0;
          }
        }
      }
    }
  }
  printf("Yes\n");
  return 0;
}
