#include <bits/stdc++.h>
using namespace std;
int main() {
  int r, c;
  cin >> r >> c;
  int s[r][c];
  for (int i = 0; i < r; i++) {
    string s1;
    cin >> s1;
    for (int j = 0; j < c; j++) {
      if (s1[j] == '.')
        s[i][j] = 0;
      else
        s[i][j] = 1;
    }
  }
  for (int i = 0; i < r; i++) {
    for (int j = 0; j < c; j++) {
      if (s[i][j] == 1) {
        for (int k = i + 1; k <= r - 1; k++) {
          if (s[k][j]) {
            for (int l = 0; l <= c - 1; l++) {
              if (s[i][l] != s[k][l]) {
                cout << "No";
                return 0;
              }
            }
          }
        }
      }
    }
  }
  cout << "Yes";
  return 0;
}
