#include <bits/stdc++.h>
using namespace std;
int n, m;
int mas[60][60];
string s;
int i, j, o;
vector<int> t;
int tlen;
int flag1;
int flag2;
int main() {
  cin >> n >> m;
  for (i = 0; i < n; i++) {
    cin >> s;
    for (j = 0; j < m; j++) {
      if (s[j] == '.') {
        mas[i][j] = 0;
      } else {
        mas[i][j] = 1;
      }
    }
  }
  t.push_back(0);
  tlen = 1;
  for (i = 1; i < n; i++) {
    for (o = 0; o < tlen; o++) {
      flag1 = 0;
      flag2 = 0;
      for (j = 0; j < m; j++) {
        if (mas[i][j] + mas[o][j] == 1) {
          flag2 = 1;
        }
        if (mas[i][j] + mas[o][j] == 2) {
          flag1 = 1;
        }
      }
      if (flag1 + flag2 == 2) {
        cout << "No" << endl;
        return 0;
      }
      if (flag1 == 1) {
        flag2 = 0;
        break;
      }
    }
    if (flag2 == 1) t.push_back(i);
    tlen++;
  }
  cout << "Yes" << endl;
  return 0;
}
