#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  cin >> n >> m;
  char cell[51][51];
  for (int row = 1; row <= n; row++) {
    string cells;
    cin >> cells;
    for (int col = 1; col <= m; col++) {
      cell[row][col] = cells[col - 1];
    }
  }
  bool achieve = true;
  set<int> covered_rows;
  set<int> covered_cols;
  for (int row = 1; row <= n && achieve; row++) {
    for (int col = 1; col <= m && achieve; col++) {
      if (cell[row][col] == '#') {
        if (covered_rows.find(row) == covered_rows.end() &&
            covered_cols.find(col) == covered_cols.end()) {
          vector<int> curr_cols;
          for (int c = col; c <= m && achieve; c++) {
            if (cell[row][c] == '#') {
              if (covered_cols.find(c) != covered_cols.end()) {
                achieve = false;
                break;
              }
              curr_cols.push_back(c);
              covered_cols.insert(c);
            }
          }
          vector<int> curr_rows;
          for (int r = row; r <= n && achieve; r++) {
            if (cell[r][col] == '#') {
              if (covered_rows.find(r) != covered_rows.end()) {
                achieve = false;
              }
              curr_rows.push_back(r);
              covered_rows.insert(r);
            }
          }
          for (vector<int>::iterator row_itr = curr_rows.begin();
               row_itr != curr_rows.end() && achieve; row_itr++) {
            for (vector<int>::iterator col_itr = curr_cols.begin();
                 col_itr != curr_cols.end(); col_itr++) {
              char color = cell[*row_itr][*col_itr];
              cell[*row_itr][*col_itr] = (color == '#') ? '.' : '#';
            }
          }
        } else {
          achieve = false;
        }
      }
    }
  }
  if (achieve) {
    cout << "Yes";
  } else {
    cout << "No";
  }
}
